Method and apparatus for testing catalytic converter durability

ABSTRACT

The present application relates in general to an apparatus and to methods for testing the performance of an automotive catalytic converter under conditions simulating those which occur in motor vehicles over extended driving conditions. The application provides a novel swirl plate and a novel fuel injector which enable the burner to run stoichiometric for extended periods of time.

RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.10/213,890 filed Aug. 6, 2002, now U.S. Pat. No. 7,140,874 which claimsthe benefit of provisional application Ser. No. 60/310,345, filed Aug.6, 2001, the contents of which are hereby incorporated in their entiretyby reference.

FIELD OF THE INVENTION

The present application relates in general to an apparatus and tomethods for testing the performance of an automotive catalytic converterunder conditions simulating those which occur in motor vehicles overextended driving conditions.

BACKGROUND

An automotive catalytic converter is an emissions control device whichmay be incorporated into the exhaust system of a motor vehicle betweenthe exhaust manifold and the muffler. The catalytic converter containsone or more catalysts, such as those based on platinum, palladium, orrhodium, which reduce the levels of hydrocarbons (HC), carbon monoxide(CO) and nitrogen oxides (NOx) in the exhaust gas, thereby reducing theamount of these pollutants which would otherwise be emitted into theatmosphere from the vehicle. In a typical commercial catalyticconverter, HC and CO in the exhaust are oxidized to form carbon dioxide(CO2) and water, and NOx is reduced to nitrogen, carbon dioxide, andwater.

As a result of recent regulatory initiatives, motor vehicle emissionscontrol devices, including catalytic converters, are now required tohave longer useful lives. For example the US Environmental ProtectionAgency (EPA) in 1996 in 40 C.F.R. 86.094-2 increased the mileage forwhich automotive emission control elements must function from 50,000 to100,000 vehicle miles. This requirement places severe demands on acatalytic converter, since a number of components introduced into thetypical automotive internal combustion engine exhaust can act as apoison to the catalyst present in the converter.

In order to understand the effects of potential catalytic convertercatalyst poisons, it is necessary to have a testing apparatus andprocedure that will permit the evaluation of the long term effects ofthe individual variables which may affect the performance of thecatalyst. Historically, an internal combustion engine has been used forsuch an evaluation, however, such an apparatus can be inconsistent,maintenance intensive, and expensive to operate. In addition, such anapparatus does not conveniently permit the separate evaluation ofindividual variables, such as the effects of constituents of the fueland of constituents of the oil. Also, the engine oil consumption varieswith engine age, operating temperature, speed and other variables, whichare difficult to control.

A test apparatus and testing method are needed which overcome theforegoing deficiencies.

SUMMARY OF THE INVENTION

In one aspect, the application provides an apparatus for aging acatalytic converter comprising: catalytic converter means; combustionmeans in fluid communication with said catalytic converter means; fuelinjection means in fluid communication with said combustion means; andlubricant injection means in fluid communication with said catalyticconverter means. The apparatus also preferably comprises: dataacquisition means; air supply means in fluid communication with saidcombustion means; and, heat exchanger means in fluid communication withsaid combustion means.

In another aspect, the application provides an apparatus for aging acatalytic converter comprising: a burner adapted to providesubstantially continuous stoichiometric combustion of a feedstream andto produce an exhaust product; a fuel injector system in fluidcommunication with said burner; a catalytic converter in fluidcommunication with said exhaust product; and, a lubricant injectionsystem in fluid communication with said catalytic converter. In apreferred embodiment, the apparatus also comprises a data acquisitionsystem adapted to provide substantially continuous fuel meteringcontrol, and preferably substantially continuous catalyst safetymonitoring.

Preferably, the burner comprises a swirl plate means. In a preferredembodiment, the swirl plate means is a swirl stabilized burner. Theswirl stabilized burner preferably comprises: a plenum chamber; acombustion tube; and, a swirl plate separating said plenum chamber andsaid combustion tube comprising an air assisted fuel spray nozzleassembly means.

In another aspect, the swirl stabilized burner comprises: a plenumchamber; a combustion tube defining a bore; and, a swirl plateseparating said plenum chamber and said combustion tube, said swirlplate being adapted to produce a pattern of collapsed conical and swirlflow in said combustion tube that defines at least one flow path alongsaid bore, preferably at least three flowpaths. In this embodiment, theswirl plate preferably comprises an air assisted fuel spray nozzleassembly in fluid communication with an air supply and a fuel supply.The air supply and fuel supply preferably are adapted to provideatomized fuel to said combustion means. The pattern produced by theswirl plate preferably collapses and expands at intervals that aresubstantially equal to the inner diameter of the burner. In theembodiment described herein, the inner diameter of the burner is about 4inches, and the pattern produced by the swirl plate preferably collapsesand expands at intervals of about 4 inches. The apparatus preferablycomprises at least one igniter in fluid communication with said at leastone flowpath, preferably at least one igniter in fluid communicationwith each of three flowpaths. The lubricant injection system preferablyis adapted to provide an atomized spray of lubricant comprising dropletshaving a sufficiently small diameter to vaporize upon exposure to saidburner. In a preferred embodiment, the diameter of the droplets is about80 microns or less, preferably about 20 microns or less.

In another aspect, the application provides a burner for producingcontinuous stoichiometric combustion of automotive fuel. The burnercomprises: a plenum chamber; a combustion tube; a swirl plate separatingsaid plenum chamber and said combustion tube comprising an air assistedfuel spray nozzle assembly means. A preferred burner is the swirlstabilized burner, described above.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a schematic diagram of one embodiment of the system.

FIG. 2A is a drawing of a preferred embodiment of a burner suitable foruse with the present application.

FIG. 2B is a close up view of the circled portion of the burner.

FIG. 3A is a frontal view of a swirl plate which imparts the desiredswirling motion to the air entering the combustion section of theburner.

FIG. 3C is a rear view of the swirl plate of FIG. 3A.

FIGS. 3B, 3D, and 3E are cross sections through the swirl plate of FIGS.3A and 3C.

FIG. 4A is a cutaway view depicting a preferred embodiment of a heatexchanger suitable for use with the present application.

FIG. 4B is a cutaway view of another section of the heat exchanger atapproximately a 90° angle to the view in FIG. 4A.

FIG. 5A is an exploded view of one embodiment of an air assisted fuelspray nozzle suitable for use in the apparatus.

FIG. 5B is a frontal view of the flanged end of the male fitting of theair assisted fuel spray nozzle of FIG. 5A illustrating an arrangement ofair injection openings.

FIG. 5C is a frontal view of the opposed end of the air assisted fuelspray nozzle of FIG. 5B.

FIG. 5D is an illustration of a preferred air assisted fuel spraynozzle.

FIG. 5E is a frontal view of the flanged end of the male fitting of theair assisted fuel spray nozzle of FIG. 5D.

FIG. 5F is a frontal view of the opposed end of the air assisted fuelspray nozzle of FIG. 5D.

FIG. 6A is a drawing depicting a preferred embodiment of an oilinjection system suitable for use with the present application.

FIG. 6B is an exploded view of the oil injection nozzle from FIG. 6A.

FIG. 7 is a block diagram of a data acquisition and control systemsuitable for use in the system.

FIG. 8 is a chart of droplet trajectories for various size droplets in adroplet distribution with an SMD of 20 microns (Example 1).

FIG. 9 is a graph showing measured, raw exhaust gas concentrations forthe present system (50 SCFM) and a Ford 4.6L, V-8 engine (50 SCFM, 1500rpm, 90 lb-ft, no EGR), both operating on the same batch of CA Phase IIfuel, at a slightly lean and a slightly rich exhaust A/F.

FIG. 10 is a schematic of a closed-loop fan control logic formaintaining the catalyst inlet temperature.

FIG. 11 shows a RAT-A simulation on FOCAS™ compared to an engine.

FIG. 12 shows a comparison of the FTP performance degradation foraverage engine and burner aged catalysts.

FIG. 13 shows THC conversion efficiency, as measured by an engine-basedcatalyst performance evaluation rig, for unaged and aged catalysts.

FIG. 14 is a speed versus time illustration of the 505 and the 867phases of the FTP driving cycle.

FIG. 15 illustrates modal THC emissions before and after aging.

FIG. 16 illustrates average FTP emissions, grouped by catalyst and age.

FIG. 17 illustrates a comparison of the FTP performance degradation forthe average engine and burner aged catalysts.

FIG. 18 illustrates the front panel control software for the burnersystem.

FIG. 19 illustrates the catalyst bed temperatures during RAT-A cycleoperation on the engine stand and on the burner rig.

FIG. 20 illustrates a schematic of prediction for impact of fuel/airstream with burner wall.

FIG. 21 illustrates a calculation of fuel spray impact on burner wall asa function of air assist angle of injection.

FIG. 22 illustrates cold-start, bag-1 results: burner and engine agedcatalysts.

FIG. 23 illustrates accumulated THC mass during cold-start, before andafter aging.

FIG. 24 illustrates accumulated NO_(x) mass during cold-start, beforeand after aging.

FIG. 25 illustrates THC emissions by aging type, catalyst, and aginghours.

FIG. 26 illustrates NMHC emissions by aging type, catalyst, and aginghours.

FIG. 27 illustrates NO_(x) emissions by aging type, catalyst, and aginghours.

FIG. 28 illustrates CO emissions by aging type, catalyst, and aginghours.

FIG. 29 shows the measured mass emission during the cold-start phase ofthe FTP.

BRIEF DESCRIPTION

The application provides a test apparatus which produces a simulatedexhaust gas with a composition and temperature corresponding to thatproduced by the internal combustion engine of a motor vehicle. Theapparatus can be used with or without using lubricating oil in itsoperation. Precise amounts of lubricating oil can be added to theexhaust gas if required. The apparatus and method are suitable for agingof an automotive catalytic converter or, if desired, a small scale corecatalytic converter over simulated extended driving conditions. Theapparatus quickly and accurately produces the effects of additives andcontaminants from the engine fuel and/or lubricant oil on the durabilityof a full scale catalytic converter over simulated periods of extendedoperation. The apparatus is capable of producing an aged convertercatalyst which can be performance tested on an actual vehicle.

As used herein the term “automotive catalytic converter” or “catalyticconverter” means a full scale emissions control device suitable forincorporation into the exhaust system of a motor vehicle between theexhaust manifold and the muffler. As used herein the term “extendeddriving conditions” means at least 50,000 vehicle miles, and morepreferably at least 100,000 vehicle miles.

As will be demonstrated herein, the present application allows forsimultaneously or separately determining the effects of additives andcontaminants in automotive fuel and in lubricant oil on the durabilityof a catalytic converter over simulated periods of extended drivingconditions. In addition, the application is capable of producing an agedcatalytic converter catalyst suitable for performance testing on anactual vehicle.

Various components of automotive fuel and lubricant oil may contributeto deterioration, or poisoning, of the catalyst in a catalyticconverter. For example, it is well known that leaded gasoline can causecatalyst poisoning, since the tetraethyl lead which has been added tothe gasoline as an antiknock compound is a known catalyst poison. Inaddition, other components of the fuel and lubricant system of aninternal combustion engine may act as catalyst poisons if they passthrough the engine and become a constituent of the exhaust. For example,if sulfur is present in the fuel, it will likely be present as acatalyst poison in the exhaust. In addition, phosphorus and zinc, ifpresent in the engine lubricant oil, may be present in the exhaust andact as catalyst poisons.

The application provides a unique apparatus, and method of using same,which is capable of separating the effects of fuel and oil, allowingprecise control of each variable. The application provides an oil freeexhaust from combustion of gasoline or other fuel, such as gasoline;synthetic gasoline; diesel; liquefied fuel produced from coal, peat orsimilar materials; methanol; compressed natural gas; or liquefiedpetroleum gas. The exhaust is provided with precise air to fuel ratiocontrol, and a separate oil atomization system for definitive isolationof the effects of fuel and of lubricant at various consumption rates andstates of oxidation. The apparatus is capable of operating over avariety of conditions, allowing various modes of engine operation to besimulated, for example cold start, steady state stoichiometric, lean,rich, cyclic perturbation, etc.

The apparatus comprises: (1) an air supply system to provide air forcombustion to the burner, (2) a fuel system to provide fuel to theburner, (3) a burner system to combust the air and fuel mixture andprovide the proper exhaust gas constituents, (4) a heat exchanger tocontrol the exhaust gas temperature, (5) an oil injection system, and(6) a computerized control system.

The Air Supply System

Referring now to the drawings and initially to FIG. 1, a schematicdiagram of the system is shown. An air blower 30 draws ambient airthrough an inlet air filter 20 and exhausts a pressurized stream of air.The air blower 30 and the mass air flow sensor 50 may be of anyconventional design which will be well known to a person of ordinaryskill in the art. In a preferred embodiment the air blower 30 is anelectric centrifugal blower, such as a Fuji Electric Model VFC404A RingBlower, and the mass air flow sensor 50 is an automotive inlet air flowsensor such as a Bosh Model Number 0280214001 available from most retailautomotive parts stores. The volume of air supplied is set by adjustinga bypass valve 40 to produce a desired flow rate of air, which ismeasured by a mass flow sensor 50.

The Fuel Supply System

A standard automotive fuel pump 10 pumps automotive fuel through a fuelline 12 to an electronically actuated fuel control valve 14 then to theburner 60 (described in more detail below). As used herein, the term“automotive fuel” means any substance which may be used as a fuel forthe internal combustion engine of a motor vehicle, including, but notnecessarily limited to, gasoline; synthetic gasoline; diesel; liquefiedfuel produced from coal, peat or similar materials; methanol; compressednatural gas; or liquefied petroleum gas.

Although other types of control valves may be used, a preferred fuelcontrol valve 14 is a solenoid valve that receives a pulse widthmodulated signal from the computer control system and regulates the flowof fuel to the burner in proportion to the pulse width. Theelectronically actuated solenoid valve 14 may be of a design which willoperate with a pulse modulated signal which will be well known to aperson of ordinary skill in the art. In a preferred embodiment theelectronically actuated fuel control valve 14 is a Bosch frequency valvemodel number 0280 150 306-850 available from most retail automotiveparts suppliers. From the fuel control valve 14 the fuel is piped to theair assisted fuel spray nozzle 16 in the burner assembly (describedbelow).

The Burner

The burner is specially fabricated, as described below to producestoichiometric combustion of the fuel and air. In a preferredembodiment, the burner 60 is a swirl stabilized burner capable ofproducing continuous stoichiometric combustion of automotive fuel.

Referring now to FIG. 2, in a preferred embodiment the burner comprisesa plenum chamber 200 and a combustion tube 210. A swirl plate 18separates the plenum chamber 200 from the combustion tube 210. Thecombustion tube 210 is constructed of material capable of withstandingextremely high temperatures. Preferred materials include, but are notnecessarily limited to INCONEL or stainless steel, and optionally can beequipped with a quartz tube in place of the INCONEL tube for visualobservation of the resulting flame pattern.

The air and fuel are separately introduced into the burner 60. Air fromthe mass flow sensor 50 is ducted to the plenum chamber 200 (FIG. 2)then through the swirl plate 18 into the burner tube. The swirl plate 18is equipped with a fuel injector 16.

Fuel Injector

In a first embodiment, an air assisted fuel spray nozzle 16 is engagedusing conventional means at the center of the swirl plate 18 inside ofthe plenum chamber 200 (FIG. 2). Fuel from the fuel supply line 14 isfed to the air assist fuel spray nozzle 16, where it is mixed withcompressed air from air line 15 and sprayed into the combustion tube 210(FIG. 2). The compressed air line 15 provides high pressure air toassist in fuel atomization.

FIG. 5A is one embodiment of the air assisted fuel spray nozzle 16. Asseen from FIG. 5A, the air assisted fuel spray nozzle 16 comprises maleand female flanged fittings which are engaged with the swirl plate 18. Avariety of suitable methods of engagement are known to persons ofordinary skill in the art. The female fitting 250 has a flanged end 252and a substantially tubular extension 251. A male fitting 254 comprisesa flanged end 256 and a substantially cylindrical extension 253 havingan opposed end 268. The cylindrical extension fits within the tubularextension of the female fitting along its length. In a preferredembodiment, the clearance 270 between the inner wall 259 of the tubularextension 251 and the outer wall 263 of the tubular extension 253 ispreferably about ⅛.″ The clearance creates a circumferential groove 257for injection of fuel, which communicates with the fuel injection hole264.

Air injection bores 262 (preferably about 1/16″) extend through theflanged end 256 and substantially parallel to the axis of the tubularextension 253 of the male fitting to a bore 260, which interfaces withthe swirl plate 18. Fuel injection bores 264 extend from the outer wall263 adjacent to the air injection bores 262 and radially inward. The airinjection bores 262 are engaged with the air line 15 in any suitablemanner. The fuel injection bores 264 are engaged with the fuel line 12in any suitable manner.

FIG. 5B is a frontal view of the flanged end 254 of the male fittingillustrating an arrangement of air injection bores 262. As seen in FIG.5B, five air injection bores 262 a-d and 265 are arranged similar to thenumeral “5” on a game die. Specifically, a line drawn through the centerof the central air hole 265 and through the center of any one of thecorner air holes 262 a-d will have 45° angle when compared to a linedrawn along 5 x-5 x in FIG. 5B. In other words, the center of the cornerair holes 262 a-d are found at the four corners of a square drawn aroundthe central air hole 265.

A frontal view of the opposed end of all parts of the air assist nozzle16 when engaged is shown in FIG. 5C. In this “bulls-eye” view: the innercircle is the bore 260 of the female fitting; the next concentric ringis the opposed end 268 of the tubular extension 253 of the male fitting;the next concentric ring is the annular groove 270 formed by theclearance between the tubular extension 251 of the female fitting andthe extension 253 of the male fitting; and, the outermost ring is theflange 252 defining a port 255.

In a preferred embodiment of the fuel injector 16 (FIG. 5D-F), likeparts are given like numbering as in FIGS. 5A-5C. Referring to FIG. 5D,the air injection bores 262 are angled to direct the fuel into the airshroud for mixing and protection, while shearing the fuel fed throughfuel injection bores 264 with injected air that passes directly throughthe fuel jet. The fuel injection bores 264 preferably are pointeddirectly into the air shroud for mixing and protection. The injectionangles maximize fuel atomization within the space requirements and workwith the swirl plate 18.

The air assisted fuel spray nozzle 16 is engaged using conventionalmeans at the center of the swirl plate 18. The air assisted fuel spraynozzle 16 comprises a flanged male fitting 252 adapted to mate with thea central bore 244 (FIG. 3C) in the swirl plate 18. In a preferredembodiment, the concentric clearance 270 between the outer wall 254 a ofthe air assisted spray nozzle and the wall 281 of the central bore ofthe swirl plate 18 is preferably from about 0.2″ to about 0.75″, mostpreferably about 0.25″. The air assisted fuel spray nozzle 16 definesair injection bores 262 having a longitudinal axis represented by lineY-Y′. Line Y-Y′ forms angles x, x′ relative to line 5F-5F, drawn alongthe inner wall 280 of the swirl plate. The angles x, x′ preferably arefrom about 65° to about 80°, preferably about 76°. The air injectionbores 262 may have substantially any configuration. In a preferredconfiguration, the air injection bores 262 are cylindrical bores.

The air injection bores 262 extend from a supply end 298 to an injectionend 299, and have an inner diameter effective to permit a suitable flowof fuel. In a preferred embodiment, the air injection bores 262 have aninner diameter of from about 0.060″ to about 0.080″, preferably about0.070″. The air injection bores 262 extend from supply end 298 to thecombustion tube 210 (FIG. 2) on the injection end 299.

The air assisted fuel spray nozzle 16 comprises a first flanged end 252a adapted to mate with the outer wall 282 of the swirl plate 18. Thealignment of the first flanged end 252 a and the outer wall 282 may takea number of configurations, such as complimentary grooves, complimentaryangles, or other types of mated machine fittings. In a preferredembodiment, the first flanged end 252 a and the outer wall 282 aresubstantially flat and parallel to one another, abutting one anotheralong a line substantially perpendicular to longitudinal axis A-B. In apreferred embodiment, the first flanged end 252 a extends radiallyoutward from the longitudinal axis, illustrated by line A-B, to adistance of from about 0.38″ to about 0.65″, preferably to a distance ofabout 0.38″ therefrom.

A second flanged end is not entirely necessary; however, in a preferredembodiment, the air assisted spray nozzle 16 further comprises a secondflanged end 252 b extending radially outward from the longitudinal axisdefined by line A-B to a distance of from about 0.3″ to about 0.45″,preferably about 0.38″ therefrom.

As shown in FIG. 5D, the first flanged end 252 a and the second flangedend 252 b define a flow chamber 297 comprising a port 255 at the supplyend 298. The configuration and size of this port 255 is not criticalprovided that the port 255 permits the flow of an adequate amount offuel through the flow chamber 297 to the fuel injection bores 264defined by the air assisted spray nozzle 16. The injection end 299 ofthe air assisted spray nozzle 16 defines the fuel injection bores 264,which extend from the flow chamber 297 to an opening 291 in the airinjection bores 262. The fuel injection bores 264 may have substantiallyany configuration as long as they deliver an adequate flow of fuel. Thefuel injection bores 264 have a longitudinal axis represented by theline R-R′, which forms angles z, z′ relative to the line 5F-5F. In apreferred embodiment, the fuel injection bores 264 are cylindrical andhave a diameter of from about 0.020″ to about 0.040″, preferably about0.031″. Preferably, angles z,z′ are from about 60° to about 80°,preferably about 73°.

In operation, fuel flows through the port 255, through the flow chamber297, and through the fuel injection bores 264 and opening 291, and isinjected into the air injection bores 262, which results in a concurrentinjection of air and fuel at the injection end 299 of the air assistedfuel spray nozzle 16. Fuel collides with air at opening 291, resultingin flow jets effective to collide with the air shroud. Materials ofconstruction and dimensions for all components of spray nozzle 16 willvary based on the process operating conditions.

As shown in FIG. 5E, the air injection bores 262 comprise openings 262a-d at the injection end 299 which are arranged like the numeral “4” ona game die. The openings 262 a-d preferably are spaced at approximately90° angles relative to one another, as illustrated by AB and A′B′.

FIG. 5F is a frontal view of the supply end 298 of the air assisted fuelspray nozzle 16. In this “bulls-eye” view: the inner circle is the bore260 and the remaining concentric rings comprise the outer face 261 ofthe second flanged end 252 b. Fuel flows from the fuel line 12 to thespray nozzle 16 through the port 255, into the fuel flow chamber 297 andthrough the fuel injection bores 264 to the air injection bores 262.

Swirl Plate

In a preferred embodiment the swirl plate 18 is capable of producinghighly turbulent swirling combustion, as shown in FIGS. 3A-E so as toprovide a complex pattern of collapsed conical and swirl flow in thecombustion area. The flow pattern created by the swirl plate 18 involvesthe interaction of a number of swirl jets 242 and 242 a-c, 253 and 253a-c and turbulent jets 248 and 248 a-c, 249 and 249 a-c, and 250 and 250a-c. The interaction of these jets creates a swirling flow thatcollapses and expands, preferably at intervals that are substantiallyequivalent in length to the inner diameter of the combustion tube 210.In a preferred embodiment, the inner diameter of the combustion tube 210is 4 inches, and the intervals at which the swirling flow collapses andexpands is every 4 inches. The pattern clearly defines flow paths alongthe wall of the combustion tube 210, which define the location of theigniters 220 along the combustion tube 210. In the embodiment describedherein, the igniters are located at the first and second full expansionsalong the path of inner swirl jets (253 a,b,c).

In a preferred embodiment, shown in FIGS. 3A-3E, the swirl plate 18 is asubstantially circular disc having a thickness sufficient to fix the airflow pattern and to create an “air shroud” that is effective to protectthe fuel injector. The thickness generally is about ½ inch or more. Theswirl plate 18 has a central bore 255. The air assisted spray nozzle 16is fitted to the swirl plate 18 at this central bore 255 using suitablemeans. In the described embodiment, the swirl plate 18 has bores 240therethrough for attachment of the air assisted spray nozzle 16. Theswirl plate 18 is made of substantially any material capable ofwithstanding high temperature, a preferred material being stainlesssteel.

The central bore 255 is defined by a wall 244. Generally speaking, eachtype of jet located at a given radial distance from the longitudinalaxis of the swirl plate has four members (sometimes called a “set” ofjets) spaced apart at approximately 90° along a concentric circle at agiven distance from the central bore 255. Three sets of turbulent jets248, 249, and 250 direct the air toward the central bore 255. The innerand outer sets of swirl jets 242, 253, respectively, direct the air fromthe outer circumference 256 of the swirl plate 18 and substantiallyparallel to a line 3C-3C or 4E-4E (FIG. 3C) through the diameter theswirl plate in the respective quadrant in the direction of the burner.

The precise dimensions and angular orientation of the jets will varydepending upon the inner diameter of the burner, which in the embodimentdescribed herein is about 4 inches. Given the description herein,persons of ordinary skill in the art will be able to adapt a swirl platefor use with a burner having different dimensions.

The orientation of the jets is described with respect to the front faceof the swirl plate 257, with respect to the longitudinal axis 241 of theswirl plate 18, and with respect to the lines 3C-3C and 4E-4E in FIG.3C, which divide the swirl plate 18 into four quadrants. Six concentriccircles 244 and 244 a-e (FIG. 3C) are depicted, beginning at theinterior with the wall 244 defining the central bore 255 and extendingconcentrically to the outer circumference 244 e of the swirl plate 18.In the embodiment described herein, the central bore has an innerdiameter of 1.25 inches, or an inner radius of 0.625 inches. A firstconcentric circle 244 a is 0.0795 inches from the wall 244; a secondconcentric circle 244 b is 0.5625 inches from the wall 244; a thirdconcentric circle 244 c is 1.125 inches from the wall 244; a fourthconcentric circle 244 d is 1.3125 inches from the wall 244; and, a fifthconcentric circle 244 e is 1.4375 inches from the wall 244.

A set of outer swirl jets are labeled 242, and 242 a,b,c. A set of innerswirl jets are labeled 253 and 253 a,b,c. The outer swirl jets 242 and242 a-c and the inner swirl jets 253 and 253 a-c have the same angle z(FIG. 3B) relative to the surface 257 of the swirl plate 18, preferablyan angle of 25°. In a preferred embodiment, both the outer swirl jets242 and 242 a-c and the inner swirl jets 253 and 253 a-c have an innerdiameter of 5/16.″ The outer swirl jets 242 direct air from an entrypoint 242 x along the outer circumference 256 of the swirl plate 18 onthe fuel injection side 59 to an exit point 242 y along circle 244 b onthe burner side 60. The longitudinal axis of the outer swirl jets 242 isparallel to and spaced 0.44 inches from lines 3C-3C and 4E-4E in theirrespective quadrants. The inner swirl jets 253 extend from an entrypoint along the circle 244 b on the fuel injection side 59 to an exitpoint on the burner side 60 along the central bore 244. The longitudinalaxis of the inner swirl jets 253 also is parallel to lines 3C-3C and4E-4E in the respective quadrants.

The air shroud jets 250 direct air from a point along the circle 244 bdirectly inward toward the center of the central bore 255. Thelongitudinal axis of the air shroud jets 250 runs along the lines (3C-3Cand 4E-4E). The angle a (FIG. 3D) of the longitudinal axis 251 of theair shroud jets 250 with respect to the longitudinal axis 241 of theswirl plate 18 is 43.5°. The air shroud jets 250 preferably have aninner diameter of about ¼inch. The exit points 242 y of the outer swirljets 242 on the burner side 60 of the swirl plate 18 preferably arealigned longitudinally, or in a direction parallel to the longitudinalaxis 241 of the swirl plate, with the entry points of the air shroudjets 250 on the fuel injection side 59 of the swirl plate 18.

The air shroud jets 250 are primarily responsible for preventing theflame from contacting the air assisted spray nozzle 16. The air flowingfrom the air shroud jets 250 converges at a location in front of thefuel injector 16 (FIGS. 1 and 2) and creates a conical shroud of airwhich results in a low pressure area on the fuel injection side 59(FIG. 1) of the swirl plate 18 and a high pressure area on the burnerside 60 of the swirl plate 18. The low pressure area on the fuelinjection side 59 helps to draw the fuel into the combustion tube 210while the high pressure area on the burner side 60 prevents the burnerflame from attaching to the face of the air assisted spray nozzle 16,and prevents coking and overheating of the nozzle 16. In a preferredembodiment, the air shroud jets 250 converge from about 0.5 cm to about1 cm in front of the nozzle 16.

The combustion tube 210 is equipped with several spark igniters 220 (seeFIG. 2). In a preferred embodiment, three substantially equally spacedigniters 220 are located around the circumference of the combustion tubein the gas “swirl path” created by the swirl plate 18. In a preferredembodiment these igniters 220 are marine spark plugs.

In an alternate embodiment, suitable for combustion of low volatilityfuels, the combustion tube 210 is further equipped with ceramic foamlocated about one foot downstream from the spray nozzle 16.Substantially any suitable foam may be used, preferably 10 pore/inch SiCceramic foam commercially available, for example, from Ultra-MetCorporation, Pacoima, Calif. 91331.

Interaction of Fuel Injector and Swirl Plate

The burner 60 and the fuel injector 16 work together to providesubstantially continuous and “effective stoichiometric combustion.” Asused herein, the term “effective stoichiometric combustion” refers tostoichiometric combustion which maintains the integrity of the wall ofthe combustion tube without substantial coking of the fuel injector. Asa result, the burner may run substantially continuously atstoichiometric for at least 200 hours without the need for maintenance.In a preferred embodiment, the burner may run substantially continuouslyat stoichiometric for at least 1500 hours with minimal maintenance. Byminimal maintenance is meant spark plug changes only.

The design of the fuel injector 16 (above) takes into account theprimary features of the swirl plate 18, namely:

-   1) The outer turbulent jets 248 and 249 (shown in Section 3C-3C)    keep the flame from remaining in constant contact with the interior    wall of the combuster tube 210. Because the burner 60 operates    continuously, and for extended times at stoichiometric (the hottest    air/fuel ratio operating point), it is necessary to maintain the    integrity of the wall of the combustion tube 210. Currently, the    INCONEL combustion tube 210 has been exposed to over 1500 hours of    operation, without showing evidence of deterioration. This feature    does not substantially affect fuel injection.-   (2) The inner swirl jets 242 set-up the overall swirl pattern in the    burner. Air exiting the inner swirl jets 242 impacts the interior    wall of the combuster tube 210 about 3 inches downstream of the    swirl plate 18, and directly interacts with the spray of fuel from    the fuel injector 16.-   (3) The inner turbulent jets 250, are sometimes referred to as the    ‘air shroud’ jets. Air exiting the inner turbulent jets 250    converges 0.75 inches in front of the fuel injector 16. This feature    provides two very important functions. The point of convergence    creates a high pressure point in the burner 60, which prevents the    burner flame from attaching to the fuel injector 16 (preventing    coking). The second function, which interacts directly with fuel    injection and impacts flame quality, is that it shears the remaining    large fuel droplets as they enter the burner flame.    The Heat Exchanger

The exhaust from the burner 60 is routed to a heat exchanger 70. Theheat exchanger 70 may be of any conventional design which will be wellknown to a person of ordinary skill in the art. In a preferredembodiment the heat exchanger 70 consists of two sections. The upstreamsection consists of a water jacketed tube. The downstream section is avertical cross flow shell and tube heat exchanger. The vertical crossflow design minimizes steam formation and steam trapping within thecooling tubes. The heat exchanger 70 is provided with an inlet waterline 80 and an outlet water line 90 which supply and drain cooling waterto cool the exhaust gas to a temperature simulating that which ispresent at the inlet to the catalytic converter of a typical motorvehicle.

Referring now to FIG. 4 which shows details of the heat exchanger of thepreferred embodiment, for the upstream section, a shell 305 is fittedwith a water inlet connection 306. The shell 305 functions as a waterjacket for an inner tube which contains the exhaust gases from theburner. Water flows through the water jacket which is fitted withseveral baffles 308 to direct the water around all parts of inner tube.At the downstream end, the shell 305 is fitted with an outlet waterconnection 309.

For the downstream section of the heat exchanger, a shell 310 is fittedwith a water inlet connection 320 which is in turn connected to an inletheader 330. The inlet header 330 is in fluid communication with aplurality of one half inch tubes 340 which extend from the bottom to thetop of the shell 310 whereupon the plurality of one half inch tubes 340are in placed in fluid communication with an outlet header 350 which isfitted with an outlet water outlet connection 360. In operation hotexhaust gas is directed through the shell 310 where the gas comes incontact with the plurality of one half inch tubes 340. Cooling water iscirculated into the inlet water inlet connection 320 whereupon it isdirected by the inlet header 330 to flow through the plurality of onehalf inch tubes 340. Heat which is present in the exhaust gas isconducted into the cooling water, producing an exhaust gas of a reducedtemperature at the outlet of the heat exchanger 70 of FIG. 1.

The Oil Injection System

The exhaust gas is next routed to an oil injection section 110 (FIG. 1).The oil injection section provides an atomized oil spray comprising oildroplets with a sufficiently small diameter to vaporize and oxidize theoil before it reaches the catalyst. The oil injection system may belocated anywhere downstream from the burner.

A series of test runs were conducted using a Malvern laser particlesizing instrument to determine the preferred oil droplet size as afunction of nitrogen pressure in the gas assist line. Suitable oildroplet sizes have a Sauter mean diameter of less than 80 microns, mostpreferably a Sauter mean diameter of about 20 microns or less.

In operation, a sample of motor oil is withdrawn from an oil reservoir150 (FIG. 1) by means of an oil pump 160. Substantially any type of pumpmay be used, preferably a peristaltic pump which feeds the oil from thereservoir through an oil injection line 140 and into a water cooledprobe 120 from which the oil is injected into the exhaust gas which ispresent in the oil injection section 110.

The oil injection system is installed in a four inch diameter pipe, andplaced in a location where the exhaust gas temperature is approximately600° C. In a preferred embodiment, the oil injection section 110 isconstructed as depicted on FIGS. 6A and 6B. In this embodiment, aseparate oil injection line 434 and nitrogen injection line 410 passthrough a coupling 430 which is threaded into the injection sectionhousing 432 and into a water cooled sleeve 420 in the injection sectionhousing 432. The oil injection line 434 communicates with the machinedoil ring 444 (FIG. 6A) of the oil injection nozzle 440. The nitrogeninjection line 410 communicate with the machined air ring 448 (FIG. 6A)of the oil injection nozzle 440. In addition to the machined oil ring 44and the machined air ring 448, the oil injection nozzle comprises amodified bolt 442, an o-ring seal 446, a stock jet 450, and a stocknozzle 452.

In operation, a coolant solution, preferably water, is continuouslycirculated through the sleeve 420, which jackets the oil injection line434 and nitrogen injection line 410, causing the oil and nitrogeninjector system to remain at the desired temperature. Lubricating oil ispumped via the oil injection line 434 into the nozzle 440, where the oilis mixed with the nitrogen. The resulting nitrogen/oil mixture isinjected into the exhaust gas through the nozzle 440. The exhaust gashaving been mixed with the injected oil is finally passed through anautomotive catalytic converter 170 following which the exhaust gas isvented to the atmosphere via an exhaust line 180.

The Computerized Control System

Referring now to FIG. 7, there is provided a data acquisition andcontrol system suitable for use with the present application. The systempreferably provides a means to control ignition, air assist to the fuelinjector, auxiliary air, fuel feed, blower air feed, oil injection, etc.(discussed more fully below). An example of a suitable control systemwould be a proportional integral derivative (PID) control loop, forexample, for controlling fuel metering.

The data acquisition system comprises a series of test probes 610, 620,630 which collect data regarding a number of parameters. Suitableparameters are selected from the group consisting of: the mass air flowin the system; the air/fuel ratio (linear and EGO); the exhaust gastemperature at the outlet from the heat exchanger; the exhaust gastemperature at the inlet to the catalyst; the exhaust gas temperature atthe outlet from the catalyst; and, a combinations thereof. In apreferred embodiment, data is collected for all of the foregoingparameters. The information measured by the test probes is transmittedby electronic signals to an electronic data recording system 650. In apreferred embodiment the electronic data recording system comprises acomputer system with a program which causes the computer to measure allof the monitored parameters on a periodic basis, to record all of thedata obtained on a hard drive.

Preferably, the data acquisition and control system monitors the teststand for safety (for example by verifying that the burner is lightedand that the exhaust is within specified limits for both temperature andair to fuel ratio). The control system contains an auto start and autoshutdown option. After the burner fuel is activated, a set of safetychecks automatically initialize and monitor the burner for malfunction.While a test is in progress the program collects data at 4 Hz, storesdata at 0.5 Hz and displays the catalyst inlet, bed, and outlettemperatures and measured air to fuel ratio at 1 Hz, allowing theoperator to review the overall stability of the system. Operating agasoline fuel burner unattended for long periods of time is potentiallydangerous. The system uses three built-in safety limits to check forsystem malfunction. The heat exchanger outlet must reach a temperaturegreater than 100° C. within four seconds after activation of fuelinjection and maintain a minimum safety setpoint level during operation,indicating that the burner is properly ignited and remains lit. Thethird setpoint checks the catalyst bed temperature to verify that thecatalyst is not at a temperature that could be detrimental to theexperiment. If any of the safety setpoints are compromised, the computeris programmed to turn off all test systems, divert the blower flow,activate a two minute nitrogen purge into the burner head to extinguishthe burner flame and suspend any unburned fuel in nitrogen, therebypreventing a large exothermic reaction in the test apparatus. A brightred screen is displayed describing the condition at which the system wasshut down, along with the date and time. Data are continuously recordedat 4 Hz for ten minutes after a safety compromise. In addition, thenitrogen purge system is also activated and a safety shutdown isfollowed when an electrical power loss is detected.

In a preferred embodiment the data acquisition and control system isalso capable of controlling a number of parameters, includingcontrolling the lube oil injection and burner systems. The computer isequipped with a touch screen monitor and a multi-function DAQ card,connected to an digital relay module to monitor and record systeminformation, and to control system electronics. Using the computerinterface, the operator can switch power to the blowers and fuel pump,as well as control the air assisted fuel injectors, burner spark, oilinjection, and auxiliary air, all with the touch of the screen. Systemtemperatures, mass air flow for the burner air, and the burner air tofuel ratio are measured and converted to engineering units. The softwareprogram uses measured data to calculate total exhaust flow and burnerair to fuel ratio, and to check conditions indicative of a systemmalfunction. The burner air to fuel ratio may be controlled as eitheropen or closed loop, maintaining either specified fuel flow or specifiedair to fuel ratio. Air to fuel ratio control is achieved by varying therate of fuel delivered to the burner (modifying the pulse duty cycle ofa fixed frequency control waveform). Whenever necessary, open loopcontrol can be activated allowing the operator to enter a fixed fuelinjector pulse duty cycle. Closed loop control can be activated in whichthe actual burner air to fuel ratio is measured and compared to themeasured value of the air to fuel setpoint and then adjusting the fuelinjector duty cycle to correct for the measured error. The front panelof the program is used to allow the user to input an aging cycle, and torun the test using a single screen.

In a preferred embodiment, the data acquisition and control system isprovided with a computer program to control the system and to acquireand process the signals from the measured parameters. The computerprogram can be written in a variety of different ways, which will bewell known to persons versed in the art. The controller preferably isprovided with a closed-loop fan control to maintain catalyst inlettemperature, preferably at from about −50° C. to about +50° C. about asetpoint temperature, preferably from about −5° C. to about +5° C. abouta setpoint temperature. The setpoint temperature is dictated by thecycle being simulated. FIG. 10 shows a schematic of a suitableclosed-loop fan control in which the controller output varies the speedof the cooling fans from off, to low, to high.

The application will be better understood with reference to thefollowing working examples, which are illustrative only.

EXAMPLE 1

A series of tests was performed to determine the droplet sizes forlubricant injected into the system. Results of droplet sizing tests areshown in FIG. 8. The figure shows the “Sauter mean diameter” of thedroplets in microns (labeled “D(3,2)”) as a function of air pressure forthe planned oil flow of 0.8 mL/min. The Sauter mean diameter (or SMD orD₃₂) is the drop diameter of an idealized monodisperse spray that hasthe same surface area-to-volume ratio as the actual polydisperse spray.The surface area-to-volume ratio correlates with the evaporation rate ofthe spray, so the SMD is a common measure of spray characteristics forevaporating or combusting sprays. The SMD is defined mathematically as:

${SMD} = {D_{32} = \frac{\sum{n_{i}D_{i}^{3}}}{\sum{n_{i}D_{i}^{2}}}}$where n_(i) is the number of drops in size class D_(i). From the figure,it can be seen that the droplet size decreases with increasing airpressure. If there were no other considerations, the highest pressurewould be used to give the smallest droplet, since it is desirable tohave as much of the oil evaporate as possible. For this apparatus,however, nitrogen, not air, was used for the “air assist” gas. Thenitrogen consumption preferably is kept at a minimum, both from anoperating cost standpoint, and to keep the percentage of nitrogen in theexhaust stream as low as possible. As a result, there is a trade-offbetween the droplet size and pressure. Acceptable pressures weredetermined during the optimization testing of the apparatus.

To assist in determining the pressure-droplet size tradeoff, a computersimulation was run using a computer program (TESS, Southwest ResearchInstitute) that calculates the amount of the liquid which will evaporateat various locations downstream of the liquid droplet injection. Thecomputer simulation assumed a 2.5 inch diameter pipe and exhaust gasflow of 50 scfm at 400° C. The oil spray had an SMD of 20 microns. Thespray half-angle with respect to the center line was 9 degrees.

FIG. 8 shows the droplet trajectories for various size droplets in adroplet distribution with an SMD of 20 microns. The larger droplets hitthe wall of the 2.5 inch diameter pipe (31.75 mm radius) atapproximately 250 mm downstream from the nozzle. With a 20 micron SMD,about 75 percent of the oil evaporates, and 25 percent impinges on thewall. With a 30 micron SMD, only 50 percent of the oil evaporates beforeimpinging on the wall. Based on this data, it is important to have theSMD as small as possible.

EXAMPLE 2

A series of tests were performed in order to demonstrate that theapparatus could provide useful information on full scale catalyticconverter durability with oil injection. The tests were performed withcatalyst bricks identified in the following Table:

Catalyst Manufacturer Englehard Designation FEX-010-M2 Size 3.268″ Dia.by 3.0″ Long Cell Density 400 cells/sq. in. Catalytic MetalsPalladium/rhodium @9:1 Metal Loading 60 g/cu. ft.

Fully formulated lubricant oils were used for the tests, by which ismeant that the lubricant oils had detergents and other additives as wellas base lube stock. The lubricant oils are described in the followingtable:

Oil No. 1 Oil No. 2 SwRI identification EM-2209-EO EM-2210-EO SAEviscosity 5W30 5W30 density, g/cu. Cm 0.867 0.865 Weight PercentPhosphorus 0.11 0.06

Modern computer controlled vehicle engines provide two modes of fuelcontrol, an open-loop control (engine crank, warm up, hardacceleration), and stoichiometric closed-loop control (part throttle andidle conditions) after the catalyst has reached operating temperature.During the closed-loop mode the engine air-fuel ratio is constantlyperturbating between slightly rich and slightly lean (due to the on-offswitch type operation of the exhaust oxygen sensor used for feedback).Performance evaluation tests were therefore conducted using simulationsof the rich open-loop (steady state) mode and the perturbatedstoichiometric closed-loop mode. The temperature at which the HC, CO andNOx conversion efficiency reached 50 percent was evaluated during therich steady-state air-fuel ratio tests, and the catalyst HC, CO, and NOxefficiency at 425° C. was evaluated during perturbated stoichiometrictests.

The results of the light-off and steady state efficiency evaluations arepresented in the table below. The data are presented in ascending orderof amount of oil injected, rather than in chronological order in whichthe catalyst was aged or evaluated.

Validation Test Results Rich Steady- Perturbated State StoichiometricOil Total Temp. ° C. at % Conversion Location Used, Oil, P, P, P, 50%Conversion @ 425° C. Core inches Hours mL mL/hr wt % grams mg/hr HC CONO_(x) HC CO NO_(x) REF N.A. 0 0 0 0 0 0 71 96 50 B4 30 25 500 20 0.110.476 19.05 374 310 314 88 98 52 B5 30 25 500 20 0.06 0.260 10.39 377312 335 88 99 47 B4(avg, 30 50 1000 20 0.11 0.953 19.05 372 313 329 8495 44 of 2) B5(avg. 30 50 1000 20 0.06 0.520 10.39 374 319 341 86 93 53of 2) B1 56 37.5 3781 100.8 0.11 3.602 96.05 382 320 330 79 88 44

The catalyst conversion efficiencies for HC, CO, and NOx from theperturbated stoichiometric tests as a function of oil injected weredetermined. For HC and CO, there was about a 10 percentage pointdecrease in conversion efficiency between the smallest amount of oilinjected and the largest amount. For NOx, there was approximately a 5percentage point decrease over the same oil injection range. Note thatwhile there were sometimes differences in conversion efficiency betweenthe 0.11 weight percent phosphorus oil and the 0.06 weight percentphosphorus oil, there was no clear correlation with the percentphosphorus.

The temperature at which 50 percent conversion efficiency was obtainedduring rich light-off as a function of oil injected was determined. Ascan be seen from the table of validation test results above there was aslight increase in the 50 percent conversion efficiency temperature forHC, CO, and NOx, indicating a slight deterioration in the ability of thecatalyst to light-off. This temperature increase was small, however. Aswas seen with the efficiency measurements, there did not appear to be ameasurable difference in light-off temperature between 0.11 and 0.06percent phosphorus oil.

It is generally assumed by those skilled in the art that it is thephosphorus in the oil which poisons the catalytic converter catalyst.Thus, for equal volumes of oil injected, one would expect that oil witha higher phosphorus level would poison the catalyst to a greater extent.This trend was not clearly evident from the validation test resultspresented above. The question thus arises as to whether there is reallyno difference in catalyst performance with varying phosphorus levels, atleast over the range tested, or whether the present application wasunable to replicate a difference that might be seen in actual engineoperation. In order to explore the catalyst performance differences morefully, the amount of phosphorus injected during each test was calculatedfrom the weight percent phosphorus, the oil density, and the volume ofoil injected. The total amount of oil and phosphorus injected, and theoil and phosphorus injection rate for each test, are also presented intable of validation test results above.

The perturbated conversion efficiencies for HC, CO and NOx,respectively, as a function of total phosphorus mass injected weredetermined. Comparing the conversion efficiencies for all emissions as afunction of phosphorus mass and as a function of oil injected, itappears that the plots against phosphorus mass show slightly less dataspread than was seen in the plots of oil consumed. This observationlends credence to the assumption that it is the phosphorus in the oilthat poisons the catalyst. The 50 percent conversion temperature for therich light-off tests as a function of total phosphorus mass weredetermined. Less data spread was seen than in previous examples.

EXAMPLE 3

Testing was done to compare the exhaust gas of a typical gasoline fueledengine to the burner system of the present application. FIG. 9 showsmeasured, raw exhaust gas concentrations for the present system (50SCFM) and a Ford 4.6L, V-8 engine (50 SCFM, 1500 rpm, 90 lb-ft, no EGR),both operating on the same batch of CA Phase II fuel, at a slightly leanand a slightly rich exhaust A/F. The A/F was calculated using themeasured raw exhaust gas composition and fuel properties; a method wellknown to those versed in the art.

FIG. 9 shows that the exhaust of the present system contains much lowerTHC and NO_(x) levels, compared to a Ford 4.6L engine. The CO level isabout half to three quarters of the engine level, and the CO₂ and O₂ areapproximately the same (as these two elements are largely controlled byAFR, not combustion conditions). THC is low because the burner is highlyefficient with steady, well vaporized fuel flow, and there are no quenchregions resulting in partial burn, as in an engine. NO_(x) is lowbecause the burner operates at near atmospheric pressure, unlike anengine in which NO_(x) is a result of the high pressure of combustion.Nevertheless, the exhaust gas of the present system can be consideredsufficiently similar to engine exhaust gas because the exhaust gas isconsidered simply a “carrier gas” for the potential catalyst poisons.

EXAMPLE 4

In order to compare the results produced by the instant application withthose which would be obtained with an actual internal combustion engine,the results were compared to those provided in Beck, D. C., Somers, J.W., and DiMaggio, C. L., “Axial Characterization of Catalytic Activityin Close-Coupled Lightoff and Underfloor Catalytic Converters”, AppliedCatalysis B: Environmental, Col. 11 (1977) pages 257-272, ElsevierScience B. V. (“Beck”). The Beck vehicle had a 3.8 liter V-6 engine withclose coupled “light-off” catalytic converters in the exhaust from eachcylinder bank of the engine, and the outlets from these were combinedinto a single pipe containing a single underfloor converter. Thelight-off catalyst contained only palladium at a loading of 75 g/cu.ft.This catalyst was similar to the catalyst used in the testing of theinstant application, as described in the first table of Example 2.

Phosphorus tends to collect more at the upstream end of the catalyst. InBeck, the three inch long light-off catalysts were cut into threesections, each one inch thick, starting at the upstream face. Asexpected, the phosphorus contained in each section decreased withdistance from the front face. A phosphorus analysis of each sectionshowed that the upstream section contained 1.6 weight percentphosphorus, the middle section 0.9 percent, and the downstream section0.25 percent phosphorus. The samples from the Beck catalysts were testedfor conversion efficiency in a synthetic gas reactor system, similar tothat employed to determine the conversion efficiencies of the instantapplication. Warmed-up performance of these samples was tested atstoichiometric air-fuel ratio and 600° C. for HC, CO, and NOxrespectively. Beck presents conversion efficiencies from three sampleswith three different levels of phosphorus poisoning, comparable to thevalidation tests of the instant application with various levels ofphosphorus. Furthermore, Beck states that “The absolute concentrationsof phosphorus and zinc are consistent with those found in . . . other .. . converter systems which have been extensively aged,” suggesting thatthe vehicle used in this study consumed oil at a relatively nominalrate. This nominal exposure for 56,000 miles is also comparable to themaximum validation test of the instant application of 100 mL/hr for 37.5hours, which is equivalent to roughly 37,500 miles of nominal exposure.Thus, it appears that the conversion efficiency results of the instantapplication can be quantitatively compared to the conversion efficiencyresults of the Beck study, assuming the maximum phosphorus rates in thatstudy and the validation tests of the instant application both representnominal oil consumption for approximately 50,000 miles.

Comparing the conversion efficiencies of HC, CO and NOx with increasingphosphorus from the two studies, there is about a 10 percent drop in HCefficiency over the data range for both sets of data. For CO efficiency,the drop is less than 10 percentage points for both sets of data. ForNOx efficiency, the overall trend of decreasing efficiency withincreasing phosphorus is the same for both data sets, but the data setfrom the Beck study has a slightly greater decrease than the data of theinstant application. The data derived from the instant application alsoshow a lower NOx efficiency than the Beck data. Overall, the data setslook remarkably similar, thus demonstrating that the instant applicationcan produce phosphorus poisoning data similar to that seen in the field.

EXAMPLE 5

The objective of this work was to develop a control method for theFOCAS™ burner system (adding subsystems if necessary) that would allowthe burner to simulate exhaust temperature, flow, and AFR created by anengine during accelerated thermal aging. Next, the methodology wasvalidated by determining if the burner system provides acceleratedthermal aging comparable to an engine. The validation portion of thestudy examined the aging differences between six like catalysts, agedusing the General Motors Rapid Aging Test version A (RAT-A) cycle. Threecatalysts were aged using a gasoline-fueled engine, and the other threeused the modified FOCAS™ burner system. Both systems were programmed torun to the engine test cycle specifications to provide identical inlettemperature, AFR profiles, and catalyst space velocity conditions. Thecatalyst performance at defined intervals and at the conclusion of theaging was measured and compared between the two systems. In addition,the variation and repeatability of the temperature and AFR control ofeach system were assessed and compared.

One industry-accepted engine-based catalyst accelerated aging cyclewhich was used as a reference point in this study is the General MotorsRapid Aging Test Version A (RAT-A) cycle. A simulation of the RAT-Acycle was run on the FOCAS™ burner system and compared to the cycle runon the engine. It was demonstrated that the burner can be used togenerate a very similar thermal profile inside the catalyst whencompared to the profile generated by the engine. The shape of thethermal excursion was reproduced, and the AFR into the catalyst could becontrolled and reproduced. Two differences were noted between the twosystems; there appeared to be some burning of the reactants in theexhaust pipe, prior to entering the catalyst in the burner system, andthe FOCAS™ burner had much tighter AFR control than the engine. Theburning of the reactants before the catalyst resulted in a slight shiftforward of the location of the peak temperature during the thermalexcursion. The thermal profiles generated by the engine and by theburner are shown in FIG. 11, along with the measured AFR for eachsystem.

The similarity was then tested by using the FOCAS™ burner system to agecatalysts. During the testing portion of the program, six catalysts wereaged for 100 hours on the RAT-A cycle; three on an engine aging stand,and three on the FOCAS™ burner system. The catalyst performance atdefined intervals and at the conclusion of the aging was measured andcompared between the two systems. In addition, the variation andrepeatability of the temperature and AFR control of each system wereassessed and compared.

The performance evaluations consisted of comparing the regulatedemissions across the Federal Test Procedure (FTP) and using anengine-based catalyst performance evaluation rig to measure the catalystconversion efficiency as a function of exhaust air/fuel ratio (AFR) andcatalyst light-off temperature. FTP emissions utilized a 1998 HondaAccord vehicle, while engine-based catalyst performance evaluations wereperformed on an engine stand.

The FTP performance evaluations showed that the burner and the engineproduced equivalent aging effects, resulting in deterioration factorsfor THC, CO, and NOx that were not statistically different between thetwo methodologies. FIG. 12 shows the average FTP performance for theengine- and burner-aged catalysts, before and after aging. Theengine-based catalyst performance evaluations revealed that the twomethodologies produced equivalent results near stoichiometric (where agasoline engine is tuned to run). However, as the AFR deviated fromstoichiometric to the rich side it was observed that burner agingresulted in a more severe aging effect for THC and CO (slight atAFR>14.1, more severe at AFR<14.05). Although the difference in thiseffect was small and shifted from the location of typical operation, itwas noted as a difference. FIG. 13 shows the measured THC conversionefficiency as a function of AFR and catalyst age.

The final catalyst evaluations involved coring the catalysts, andanalyzing the surface area and composition. The two analyses run wereBET (Bruhauer-Emmett-Teller) for assessment of surface area andporosity, and PIXE (Proton-Induced X-Ray Emissions) for compositionalanalysis. The BET test provides information on the surface area of thesubstrate and washcoat. This analysis can be correlated to thermaldegradation. PIXE provides information on the composition of thesubstrate, washcoat, and any deposits on the surface of the catalyst.PIXE analysis can provide information on the differences in the depositson the catalysts between the engine and the burner (which providesoil-free aging). It was found that the catalysts were composed of verysimilar levels of washcoat, but that the FOCAS™ aged catalysts had anobvious absence of oil-derived deposits. However, the levels of oildeposits found on the engine-aged catalysts were small, and it is likelythat they did not impact performance.

Overall, it was found that the FOCAS™ burner system provided a flexiblemeans for simulating the engine aging cycle, and produced thermal agingresults equivalent to the engine cycle. The post-mortem analysis showsthat the FOCAS™ aging provides thermal aging in the absence ofnon-thermal aging (i.e. oil deposits), thereby creating a means for thedefinitive isolation of thermal and non-thermal aging effects. Someadvantages that using a burner offers over an engine for aging include:very tight AFR control (±0.02 AFR), very broad range of stable AFRoperation (8:1 to 25:1), few moving parts (a blower and a fuel meteringvalve), and minimal adjustments to achieve setpoints. Also, a burner canbe run at very high temperatures without severely damaging the systemcomponents, making for a low cost, low risk simulation ofvery-high-temperature cycles.

EXAMPLE 6

Seven general design criteria/guidelines were used to design preferredfuel injector. These criteria were:

-   1) Pressure in the air channel could not exceed pressure in the fuel    channel or fuel flow would be interrupted. Assuming the burner flow    is steady-state (a reasonable assumption):

${{For}\mspace{14mu}{Air}\text{:~~}\frac{P_{1_{A}}}{A_{1_{A}}} \times A_{2_{A}}} = P_{2_{A}}$${{For}\mspace{14mu}{Fuel}\text{:~~}\frac{P_{1_{f}}}{A_{1_{f}}} \times A_{2_{f}}} = P_{2_{f}}$

-   2) Desired fuel inlet pressure (based on fuel pump specifications)    is 40 psig<P_(f)<60 psig.-   3) The area of the fuel jets must provide adequate fuel flow for the    required flow range, in the given operating pressure range.-   4) The size of the fuel holes must be a standard drill bit size, and    must be large enough to allow machining without excessive    difficulty.-   5) Fuel/Air spray should aim for outer air shroud convergence to    keep the burner flame off the combustor wall as long as possible.-   6) Direct point of fuel jet convergence behind air shroud.    Adjustment Of P_(A) can be used to vary the position of the fuel    spray relative to the air shroud.-   7) Keep interaction point of the fuel and the air jet at the center    of the combined outlet hole to prevent driving the fuel spray to the    inner wall of the injector. This would lead to dripping, and coking    of the face of the injector.-   8) The degree of atomization and stability was determined visually,    using the quartz combustor. The assessment was based on the blueness    of the flame (orange flames indicated sooty conditions), the soot    forming potential (assessed by examining the injector, combustor,    heat exchanger and exhaust pipe), and the stability of the flame    (assessed using a linear AFR sensor).

Since the burner is designed to operate predominantly at stoichiometric,the required fuel flow was calculated using the required total exhaustgas flow and the stoichiometric AFR of the fuel used for aging. Thefollowing analysis presents the calculation of the required fuel flowfor the burner operating at stoichiometric, with a total exhaust flow of70 SCFM.m_(exh)=70 SCFM=2.3015 kg/minm _(fuel) =m _(exh) ×AFR _(stoich) ⁻¹×1 lb/0.45359 kg×60 min/hrm_(fuel)=21.28 lb/hr at stoichiometricm _(air) =m _(fuel)×(AFR _(avg) /AFR _(stoich))AFR _(avg)=(16/60×13)+(44/60×14.4)=14.03 RAT-A cyclem_(air)=65.1 SCFMTherefore, the rate of energy consumption of the burner over the cycleis:Q=m _(fuel)×Energy content of fuelQ=m _(fuel)×18,400 BTU/lb=21.28 lb/hr×hr/3600 sec×18,400 BTU/lb×1.055KJ/BTUQ=115 kW

Referring to FIG. 20, the distance l₁ is the radius of the combustortube, and l₂ is the distance to impact with the inner wall of thecombustion tube 210. The distance l₂ can be calculated using geometry,but then is corrected for interaction with the fuel jet (which tends tolengthen l₂) and the inner swirl jets 242 (which tend to shorten l₂).The inner swirl jets 242 have the greatest impact. The final angle forX,X′ is a function of fuel shearing and atomization (which is improvedwith lower X,X′) and preventing impact with the wall of the combustiontube 210 by directing the fuel spray into the area where the outer swirljets 253 in FIG. 3 converge (about four to five inches from the face ofthe swirl plate). These outer swirl jets 253 help to keep the hottestpart of the flame off the inner wall of the combustion tube 210, whichenables the burner to run stoichiometric for extended periods of time.Table 1 shows calculated impact of the fuel spray with the wall of thecombustion tube 210, with and without swirl jet interaction. From thesedata, two fuel injectors were built, E-62 and E-76 (where the numberrefers to the angle X,X′ in degrees).

TABLE 1 Air Injection Calc. Impact Distance Angle, Calc. ImpactDistance, Observed with Medium X, X′ No Interaction, in. Impact, in.Interaction, in. 60 2.75 2.5 61 2.88 2.57 62 3.03 2.64 63 3.18 2.71 643.34 2.8 65 3.52 2.89 66 3.71 2.98 67 3.92 3.08 68 4.14 3.25-3.5 3.2 694.38 3.32 70 4.65 3.45 71 4.95 3.6 72 5.27 3.76 73 5.63 3.94 74 6.044.14 75 6.5 4.37 76 7.02 4.64 77 7.62 4.94 78 8.32 5 5.29 79 9.15 5.7 8010.13 6.19

Experiments were performed to develop a control method for the FOCAS™burner system (adding subsystems if necessary) that would allow theburner to simulate exhaust temperature, flow, and AFR created by anengine during accelerated thermal aging. The methodology was validatedby determining if the burner system provided accelerated thermal agingcomparable to an engine. The validation portion of the study examinedthe aging differences between six like catalysts, aged using the GeneralMotors Rapid Aging Test version A (RAT-A) cycle. Three catalysts wereaged using a gasoline-fueled engine, and the other three used themodified FOCAS™ burner system. Both systems were programmed to run tothe engine test cycle specifications to provide identical inlettemperature, AFR profiles, and catalyst space velocity conditions. Thecatalyst performance at defined intervals and at the conclusion of theaging was measured and compared between the two systems. In addition,the variation and repeatability of the temperature and AFR control ofeach system were assessed and compared.

The baseline performance of the systems was tested using a engine-basedcatalyst performance evaluation rig. Catalyst performance is measured asa function of exhaust air/fuel ratio and exhaust gas temperature. Thecatalysts were degreened by operating for four hours on the RAT-A engineaging cycle. Each catalyst's performance was then reevaluated. Eachsystem was then installed on the vehicle and two Federal Test Procedures(FTP) evaluations were performed. The FTP is a chassis-based vehicleemissions test cycle, used for certifying vehicle emissions and fueleconomy. The emissions from the FTP cycle are regulated by EPA accordingto vehicle type. Six catalysts with closest performance were selectedand randomly assigned to be engine or burner aged. The seventh catalystwas the ‘set-up’ catalyst.

Test Equipment and Procedures

A certification grade California Phase II gasoline obtained fromPhillips 66 was used as the test fuel throughout all vehicle testing.The following Table gives the supplier analysis of this fuel.

Specification Supplier Item ASTM Unleaded Analyses Octane, researchD2699 93 (min.) 97.7 Sensitivity 7.5 (min.) 10.3 Pb (organic), g/U.S.gal D3237 0.050 NR Distillation Range: IBP° F. D86 75-95 104 10% Point,° F. D86 130-150 143 50% Point, ° F. D86 200-230 206 90% Point, ° F. D86290-310 292 EP, ° F. D86 390 (max.) 375 Sulfur, wt. % D1266 0.10 (max.)31 Phosphorus, g/U.S. gal. D3231 0.005 (max.) 0.001 RVP, psi D3236.7-7.0 6.8 Hydrocarbon Composition: Aromatics, % D1319 23-25 (max.)23.5 Olefins, % D1319 4-6 (max.) 5.95 Saturates, % D1319 a — a RemainderNR—Not reportedA pump grade California Phase II gasoline was used for aging andperformance evaluations. The difference between the two fuels was thatthe pump grade had detergents that prevented engine deposits.A. Chassis Dynamometer Testing

All emissions tests were conducted in accordance with the EPA FederalTest Procedure (FTP), which utilizes the Urban Dynamometer DrivingSchedule (UDDS). The UDDS is the result of more than ten years of effortby various groups to translate the Los Angeles smog-producing drivingconditions to chassis dynamometer operations, and is a nonrepetitivedriving cycle covering 7.5 miles in 1372 seconds with an average speedof 19.7 mph. Its maximum speed is 56.7 mph.

An FTP consisted of a cold-start, 505-second, cold transient phase (Bag1), followed immediately by an 867-second stabilized phase (Bag 2).Following the stabilized phase, the vehicle was allowed to soak for 10minutes with the engine turned off before proceeding with a hot-start,505-second, hot transient phase (Bag 3) to complete the test. For a3-bag FTP, the distance traveled was 11.1 miles at an average speed of21.6 mph. The vehicle's exhaust was collected, diluted, and thoroughlymixed with filtered background air to a known constant volume flowrateusing a positive displacement pump. This procedure is known as ConstantVolume Sampling (CVS). A proportional sample of the dilute exhaust wascollected in a sample bag for analysis at the end of the test. Theemissions were mathematically weighted to represent the average ofseveral 7.5 mile trips made from cold and hot starts. A speed versustime illustration of the 505 and 867 phases of the FTP driving cycle isgiven in FIG. 14. A summary of cycle duration, driving distance, andaverage speed is given in the following Table:

Duration, Distance, Average Speed, Segment seconds miles mph TransientPhase 505 3.60 25.7 Stabilized Phase 867 3.90 16.2 UDDS Total 1372 7.5019.7 (FTP CYCLE IS UDDS + HOT-START TRANSIENT 505)Exhaust emissions from the FTP cover the effects of vehicle and emissioncontrol system warn-up as the vehicle is operated over the cycle. The“stabilized” phase produces emissions from a fully warmed up orstabilized vehicle and emission control system. “Hotstart” or “hottransient” phase emissions result when the vehicle is started after thevehicle and emission control systems have stabilized during operation,and are then soaked (turned off) for 10 minutes.

Weighted total emissions from the FTP at 68° F. to 86° F. ambienttemperature conditions are regulated by the EPA. The only regulatedpollutant for the FTP at cold conditions (20° F.) is carbon monoxide(CO). Tier 1 cold-CO level for passenger cars is 10.0 g/mile. TheCalifornia ULEV emissions standards for 1998 light-duty passenger cars,intermediate life—50,000 miles (the standards which the test vehicle wascertified to) are:

NMOG: 0.04 g/mile CO:  1.7 g/mile NO_(x):  0.2 g/mileThe weighted total mass equivalent emissions for the EPA FTP-75 arecalculated as required in the U.S. EPA regulations (40 CFR 86.144-90)using the following equation:

${{Weighted}\mspace{14mu} g\text{/}{mile}} = {{0.43 \times \frac{{{Phase}\mspace{14mu} 1\mspace{14mu}{grams}} + {{Phase}\mspace{14mu} 2\mspace{14mu}{grams}}}{{{Phase}\mspace{14mu} 1\mspace{14mu}{miles}} + {{Phase}\mspace{14mu} 2\mspace{14mu}{miles}}}} + {0.57 \times \frac{{{Phase}\mspace{14mu} 3\mspace{14mu}{grams}} + {{Phase}\mspace{14mu} 2\mspace{14mu}{grams}}}{{{Phase}\mspace{14mu} 3\mspace{14mu}{miles}} + {{Phase}\mspace{14mu} 2\mspace{14mu}{miles}}}}}$

After each aging set was completed, the catalysts were installed on thetest vehicle and retested over the FTP test cycle to obtaindeterioration information. The before and after aging FTP results werethen compared to quantify a deterioration factor for each catalyst. TheFTP results, averaged by catalyst and aging condition, are given inTable 11.

TABLE 11 COLD-BAG AND WEIGHTED FTP RESULTS, BEFORE AND AFTER AGING FuelTest ID Aging Emissions, grams Economy, Catalyst Start THC NMHC CONO_(x) mpg FTP Bag 1 Engine Cat-E1  0-hr 0.75 0.70 5.72 1.84 22.3 EngineCat-E2  0-hr 0.76 0.71 6.36 1.58 22.4 Engine Cat-E3  0-hr 0.67 0.62 5.231.66 22.6 FOCAS ™ Cat-B1  0-hr 0.73 0.68 5.30 1.58 22.7 FOCAS ™ Cat-B2 0-hr 0.78 0.73 6.68 1.56 22.2 FOCAS ™ Cat-B3  0-hr 0.76 0.70 6.03 1.7122.5 Engine Cat-E1 100-hr 0.94 0.87 8.49 2.47 23.2 Engine Cat-E2 100-hr0.94 0.85 8.63 2.65 22.8 Engine Cat-E3 100-hr 0.99 0.91 8.70 2.56 22.9FOCAS ™ Cat-B1 100-hr 0.95 0.89 7.93 2.62 22.6 FOCAS ™ Cat-B2 100-hr1.01 0.94 8.10 2.44 22.3 FOCAS ™ Cat-B3 100-hr 1.05 0.98 8.87 2.63 22.1Weighted FE, Weighted FTP Emissions Results, g/ml mpg Engine Cat-E1 0-hr 0.050 0.044 0.387 0.168 23.2 Engine Cat-E2  0-hr 0.050 0.045 0.4420.151 23.3 Engine Cat-E3  0-hr 0.045 0.040 0.381 0.154 23.4 FOCAS ™Cat-B1  0-hr 0.048 0.042 0.409 0.151 23.5 FOCAS ™ Cat-B2  0-hr 0.0520.046 0.503 0.149 23.2 FOCAS ™ Cat-B3  0-hr 0.050 0.044 0.461 0.146 23.5Engine Cat-E1 100-hr 0.069 0.058 0.695 0.253 24.1 Engine Cat-E2 100-hr0.067 0.055 0.738 0.257 23.8 Engine Cat-E3 100-hr 0.070 0.060 0.6310.249 23.0 FOCAS ™ Cat-B1 100-hr 0.068 0.058 0.579 0.252 23.5 FOCAS ™Cat-B2 100-hr 0.075 0.062 0.732 0.268 23.3 FOCAS ™ Cat-B3 100-hr 0.0730.062 0.698 0.279 23.0

FIG. 15 shows the accumulated tailpipe mass hydrocarbon (THC) for allthe FTP tests before and after aging. FIG. 15A is the degreened catalystfor which aged results are given in 15C. FIG. 15B is the degreenedcatalyst for which aged results are given in 15D. A closer examinationof the feedgas THC during cold-start (also shown in FIG. 15) revealsthat it is the engine-out variation that causes the tailpipe variation.The modal emissions were then used to calculate vehicle air-fuel ratio(AFR).

FIG. 16 shows a comparison of the weighted FTP emissions for theconverters before and after aging. FIG. 17 compares the averageperformance of the engine-aged catalysts to the burner-aged catalysts.There was some degradation in THC, but the largest impact was on NO_(x)mass emission (largely due to the positioning of the catalyst on thevehicle). There also appeared to be very similar degradation impacts onboth sets of catalysts. Table 12 gives the calculated deteriorationfactors for each of the regulated emissions by type of aging. Thedeterioration factor was calculated from the average performance of eachcatalyst, using the following equation:

TABLE 12 PERFORMANCE DETERIORATION FACTOR BY CATALYST AND GROUP$1 + \left\lbrack \frac{M_{aged} - M_{unaged}}{M_{unaged}} \right\rbrack$Deterioration Factor Catalyst Group NMHC CO NOx Catalyst E1 1.31 1.791.50 Catalyst E2 1.24 1.67 1.70 Catalyst E3 1.57 1.92 1.74 AverageEngine Aged 1.37 1.80 1.65 Standard Deviation 0.18 0.13 0.13 ofDegradation Catalyst B1 1.38 1.42 1.67 Catalyst B2 1.30 1.25 1.67Catalyst B3 1.43 1.51 1.92 Average Burner Aged 1.37 1.39 1.75 StandardDeviation 0.06 0.13 0.14 of DegradationReviewing Table 12 reveals that both aging methods produced equivalentimpact on NMHC emissions, but the burner-aged catalysts had lessvariation in calculated deterioration. There also appeared to be adifference in the NO_(x) deterioration factors, but the difference wasnot statistically significant. Also, in examining the NO_(x) performanceof each catalyst, it can be seen that catalyst B3 appeared to havepoorer NO_(x) performance, and sustained the greatest deterioration forNO_(x). This performance outlier will also appear in the AFR sweep data,and will be presented in the next section.B. Accelerated Thermal Aging Cycle

The accelerated thermal aging procedure that was used in this work isthe published: Sims, G., Sjohri, S., “Catalyst Performance Study UsingTaguchi Methods,” SAE 881589; Theis, J., “Catalytic Converter DiagnosisUsing the Catalyst Exotherm,” SAE 94058; Ball, D., Mohammed, A.,Schmidt, W., “Application of Accelerated Rapid Aging Test (RAT)Schedules with Poisons: The Effects of Oil Derived Poisons, ThermalDegradation, and Catalyst Volume on FTP Emissions,” SAE 972846, each ofwhich is incorporated herein by reference. General Motors Rapid AgingTest version A (RAT-A) cycle. One hundred hours of aging on the GM RAT-Acycle has been correlated to 100,000 miles of on-road operation for someplatforms, but, precise miles to hours correlation for experimentalcomponents and other platforms is unknown. However, 100 hours of agingon the GM RAT-A cycle does demonstrate a level of durability that isaccepted by industry. The following Table outlines the GM RAT-A agingschedule.

Mode Mode Length, No. Description Parameter Specification sec 1Closed-loop, Stoichiometric AFR Inlet Temperature = 800° C. 40 2Open-loop, Fuel-Rich Operation, AFR~13:1 (3% CO) 6 Power enrichment 3Open-loop, Fuel-Rich Operation, AFR~13:1 (3% CO) 10 with Air InjectionO2 = 3% (target a 160°-200° exotherm - engine set first, burner set tomatch) 4 Closed-loop, Stoichiometric AFR Stoichiometric Exhaust out of 4with Air Injection engine(burner) with continued air injection Exothermin Step 3 is measured on catalyst centerline, 1 inch deepThe foregoing schedule describes exhaust and catalyst conditions, anddoes not specify how the engine is set to achieve those conditions;therefore, the same specifications that are used to set up the engineaging were used to set up the burner aging. During aging, exhaust gasAFR and temperature as well as catalyst temperatures were monitored at 1Hz and stored to file for post processing.C. Test Vehicle

The test vehicle for the program was a 1998 Honda Accord with 2.3L 4cylinder VTEC engine, certified to California ULEV standards. Thefollowing Table provides vehicle information, and emissionscertification data:

VIN 1HGCG6672WA165200 Engine Description 2.3L SOHC I-4 16-valve VTECEngine No. F23A4-1016788 Engine Family WHNXV02.3PL4 Transmission 4-speedautomatic Inertia Weight, lbs 3375 City Fuel Economy (cert) 23 mpgHighway Fuel Economy (cert) 30 mpg Emissions Certification Level 1998California ULEV FTP Certification Emission levels at 50,000 miles,grams/mile NMOG 0.0249 NO_(x) 0.0594 CO 0.2919E. Test Catalysts

The catalysts used were 1997 Honda Civic ULEV production catalysts. Pastexperience with these catalysts has indicated that they generate veryrepeatable results and appear to be produced to very tightspecifications. The Civic ULEV catalysts are manifold mounted and aresupplied attached to exhaust manifolds. After receiving the parts, thecatalysts were removed from the original mounting and then canned in“take apart” canisters to allow for easy installation on the aging andperformance test stands and selection of the position of the catalyst onthe vehicle. The catalyst position was moved from manifold mount tounderbody in order to reduce exhaust gas temperatures into thecatalysts, which should delay cold-start light-off (initiation ofactivation). Because this program's objective was to carefully comparethe effects of thermal deactivation between two aging methods, thedelayed light-off should prove beneficial in discerning the variationsin catalyst aging more accurately.

F. Engine Aging Stand

Aging was performed using a Ford 7.5L V-8 engine. Oil consumption wasalso monitored during aging.

G. FOCAS™ Rig

The burner of the FOCAS™ Rig is a flexible fuel device, and was set torun on gasoline. Air flow provided to the burner was preset by theoperator and did not vary throughout the test. The computer controlledthe burner AFR by modifying the fuel delivered to the air assistedinjection system. The burner system created a very stable steady-state,constant pressure burn that, with gasoline, was capable of operatingwith a large turn-down ratio (range of AFR operation is 8:1 to 25:1).Continuous operation at stoichiometric could be conducted for at leasttwo hundred hours, preferably for 1500 hours or more, with minimalmaintenance. Burner operation could be adjusted to achieve flows rangingfrom 20 to 70 SCFM (operated at 50 SCFM for this work), and the rig hasa preprogrammed, cold-start simulation mode to allow the effects ofcold-start to easily be added to an aging cycle.

FIG. 9 shows measured, raw exhaust gas concentrations for the FOCAS™system (50 SCFM) and a Ford 4.6L, V-8 engine (50 SCFM, 1500 rpm, 90lb-ft, no EGR), both operating on the same batch of CA Phase II fuel, ata slightly lean and a slightly rich steady-state exhaust A/F (measuredusing the Urban A/F method). The Urban AFR calculation method calculatesexhaust AFR using the measured raw exhaust gas composition and fuelproperties.

FIG. 9 shows that the FOCAS™ Rig exhaust contains much lower THC andNO_(x) levels, compared to a Ford 4.6L engine. The CO level is abouthalf to three quarters of the engine level, and CO₂ and O₂ areapproximately the same (as these two constituents are largely controlledby AFR, not combustion conditions). THC is low because the burner ishighly efficient with steady, well vaporized fuel flow, and there are noquench regions resulting in partial burn, as in an engine. NO_(x) is lowbecause the burner operates at near atmospheric pressure, unlike anengine in which NO_(x) is a result of the high pressure andcorresponding high peak temperature of combustion.

The control system for the FOCAS™ Rig consists of a Lab VIEW-programmedPC equipped with a touch screen monitor and a multi-function DAQ card,connected to an SCXI chassis holding two SCXI 1120 multiplexing modules,one feed-through panel, and an SCXI 1160 “relay module” to monitor andrecord system information, and to control system electronics. Using thecomputer interface, the operator can switch power to the blowers andfuel pump, as well as control the air assisted fuel injectors, burnerspark, oil injection, and auxiliary air, all with the touch of a finger.

System temperatures, mass air-flow for burner air, and the burner AFRwere measured and converted to engineering units. The software usesmeasured data to calculate total exhaust flow and burner AFR, and tocheck conditions indicative of a system malfunction. The burner AFR canbe controlled as either open or closed loop, maintaining the specifiedA/F. A/F control is achieved by varying the rate of fuel delivered tothe burner (modifying the pulse duty cycle of a fixed frequency controlwaveform). Whenever necessary, open loop control was achieved byallowing an operator to enter a fixed fuel injector pulse duty cycle(pulse width). Closed loop control was achieved by measuring the actualburner A/F (using a UEGO sensor), comparing the measured value to theA/F setpoint, and then adjusting the fuel injector duty cycle to correctfor the measured error. The front panel of the program was designed toallow users to input an aging cycle, and to run the test using a singlescreen. The controller contained an ‘auto start’ and ‘auto shutdown’options to allow for ease of operation. After the burner fuel wasactivated, a set of safety checks automatically initialized andmonitored the burner for malfunction. While a test was in progress, theprogram collects data at 4 Hz, stored data at 0.5 Hz, and displayed thecatalyst inlet, bed, and outlet temperatures and measured A/F ratio at 1Hz, allowing the operator to review the overall stability of the system.

FIG. 18 shows the front panel of the control software. The front paneldepicted the layout of the actual test system and the location and valueof the measured data at each point in the system. Due to the potentialdanger of operating a gasoline-fueled burner unattended for long periodsof time, the system used three built-in safety limits that checked forsystem malfunction. First, the heat exchanger outlet had to reach atemperature greater than 100° C. within four seconds after activation offuel injection, and had to maintain a minimum safety setpoint levelduring operation, which indicated that the burner was properly ignitedand remained lit. The third setpoint checked the catalyst bedtemperature to verify that the catalyst was not at a temperature thatcould be detrimental to the experimental part. If any of the safetysetpoints were compromised, the computer was programmed to turn off alltest systems, divert the blower and activate a two minute N₂ purge intothe burner head (to blow out the burner and suspend any unburned fuel inN₂, thereby preventing a large exothermic reaction in the test piece),and to display a bright red screen describing the condition at which thesystem was shut down, along with the date and time, and data which wererecorded at 4 Hz for ten minutes after a safety had been compromised. Inaddition, the N₂ purge system was also activated and a safety shutdownwas followed when an electrical power loss was detected, thereby makingit safe to operate the rig during questionable weather conditions.

B. RAT-A Simulation on FOCAS™ Rig

The RAT-A cycle is characterized mainly by steady-state, stoichiometricoperation and short thermal excursions (specifications givenpreviously). The thermal excursions were created by operating rich, togenerate about 3 percent carbon monoxide (CO), while injecting secondaryair (about 3 percent oxygen, O₂) in front of the catalyst. The excessreductants and oxidants reacted in the catalyst, releasing the chemicalenergy in the form of heat. The catalyst inlet temperature and exhaustgas flow rate were also used to specify the test cycle setup. The flowwas specified in scfm, 70 scfm was used in this work.

On the engine, the flow specification was set up by adjusting enginespeed. The gas temperature at the inlet to the catalyst was achieved byadjusting engine load (throttle position) during the steady-state,stoichiometric portion of the cycle. The thermal excursion was createdby adjusting engine operating AFR during the rich portion of the cycle,and adjusting air injection to achieve the 3 percent CO and O₂specification.

On the burner, flow was modified by changing the setting of the burnerbypass valve, and catalyst inlet gas temperature was adjusted byincreasing or decreasing the number of heat exchanger units, the flowthrough the units, and air cooling of the exhaust section between theheat exchanger outlet and catalyst inlet. Coarse gas inlet temperaturecontrol was achieved with the heat exchanger, while fine control camefrom air cooling of the exhaust section.

FIG. 19 shows measured exhaust gas and catalyst bed temperatures duringengine and burner aging. Also shown is the measured AFR at engine andburner outlet. The upper left corner shows the RAT-A cycle on theengine, and the upper right corner shows the RAT-A cycle on the FOCAS™.The bottom two graphs show the burner and the engine characteristicscompared directly to each other. The outlet thermocouples are inslightly different locations, and should not be compared.

The bottom right graph shows a comparison of the catalyst inlet and bedtemperatures during the cycle. The bed temperatures were very similarbetween the two aging systems. However, the effect of the fuel cut andthe air injection produced different inlet temperature profiles betweenthe two systems. The burner showed the drop in temperature (from to therich excursion) more quickly, but then showed a higher temperature intothe catalyst during the rich with air portion of the cycle. This wasindicative that some of the reactants were burning in the pipe beforeentering the catalyst. This burning may be a result of differences inthe way the air was injected between the two systems, and it results inone effect, the potential impact of which is not fully understood. Theeffect is that the peak temperature in the catalyst was observed at 0.5″in the burner catalyst, as opposed to 1.0″ in the engine catalyst(compare FIGS. 19A and 19B). FIG. 19C shows the measured exhaust AFR andcatalyst bed temperature (1.0″ depth). Comparing the AFR control, it canbe seen that the burner had much tighter AFR control than the engine.The other characteristic noted in the graph is that during the thermalexcursion the burner went richer than the engine. This was necessary toovercome the burning in the pipe, and to maintain the thermal excursionin the catalyst. Overall, the difference in the ability to generatereactants and resulting catalyst bed temperature between the two systemswas very small.

However, there was one control factor that began to appear as a problemfor the burner system as the program progressed. The problem was slightvariations in catalyst inlet temperature from day-to-day andday-to-night. The cause of the problem appeared to be variations in theair cooling of the section between the heat exchanger and catalystinlet. The fine tuned catalyst inlet temperature was controlled byvarying the amount of exhaust insulation, and the placement of thecooling fans at the beginning of each test. However, as the testprogressed, it was found that variations in cooling tower water and theair conditions in the new cell created conditions that could varysubstantially day-to-night, and day-to-day. This allowed the catalystinlet temperature to vary by up to 20° C. For this reason, a closed-loopfan control was created and embedded in the FOCAS™ controller. FIG. 10shows a schematic of the closed-loop fan control created for catalystinlet temperature. The controller output varies the speed of the coolingfans from off, to low, to high.

EXAMPLE 6

Seven general design criteria/guidelines were used to design thispreferred fuel injector. These criteria were:

-   1) Pressure in the air channel could not exceed pressure in the fuel    channel or fuel flow would be interrupted. Assuming the burner flow    is steady-state (a reasonable assumption):

${{For}\mspace{14mu}{Air}\text{:~~}\frac{P_{1_{A}}}{A_{1_{A}}} \times A_{2_{A}}} = P_{2_{A}}$${{For}\mspace{14mu}{Fuel}\text{:~~}\frac{P_{1_{f}}}{A_{1_{f}}} \times A_{2_{f}}} = P_{2_{f}}$

-   2) Desired fuel inlet pressure (based on fuel pump specifications)    is 40 psig<P_(f)<60 psig.-   3) The area of the fuel jets must provide adequate fuel flow for the    required flow range, in the given operating pressure range.-   4) The size of the fuel holes must be a standard drill bit size, and    must be large enough to allow machining without excessive    difficulty.-   5) Fuel/Air spray should aim for outer air shroud convergence to    keep the burner flame off the combustor wall as long as possible.-   6) Direct point of fuel jet convergence behind air shroud.    Adjustment of P_(A) can be used to vary the position of the fuel    spray relative to the air shroud.-   7) Keep interaction point of the fuel and the air jet at the center    of the combined outlet hole to prevent driving the fuel spray to the    inner wall of the injector. This would lead to dripping, and coking    of the face of the injector.-   8) The degree of atomization and stability will be determined    visually using the quartz combustor. The assessment was based on the    blueness of the flame (orange flames indicating sooty conditions),    the soot forming potential (assessed by examining the injector,    combustor, heat exchanger and exhaust pipe), and the stability of    the flame (assessed using a linear AFR sensor).

Since the burner is designed to operate predominantly at stoichiometric,the required fuel flow can be calculated using the required totalexhaust gas flow and the stoichiometric AFR of the fuel used for aging.The following analysis presents the calculation of the required fuelflow for the burner operating at stoichiometric, with a total exhaustflow of 70 SCFM.m_(exh)=70 SCFM=2.3015 kg/minm _(fuel) =m _(exh) ×AFR _(stoich) ⁻¹×1 lb/0.45359 kg×60 min/hrm_(fuel)=21.28 lb/hr at stoichiometricm _(air) =m _(fuel)×(AFR _(avg) /AFR _(stoich))AFR _(avg)=(16/60×13)+(44/60×14.4)=14.03 RAT-A cyclem_(air)=65.1 SCFMTherefore, the rate of energy consumption of the burner over the cycleis:Q=m _(fuel)×Energy content of fuelQ=m _(fuel)×18,400 BTU/lb=21.28 lb/hr×hr/3600 sec×18,400 BTU/lb×1.055KJ/BTUQ=115 kW

Referring to FIG. 20, the distance l₁ is the radius of the combustiontube 210, and l₂ is the distance to impact with the wall. The distancel₂ can be calculated using geometry, but then is corrected forinteraction with the fuel jet (which tends to lengthen l₂) and the innerswirl jets 242 (which tend to shorten l₂). The inner swirl jets 242 havethe greatest impact. The final angle for X,X′ is a function of fuelshearing and atomization (which is improved with lower X,X′) andpreventing impact with the wall of the combustion tube 210 by directingthe fuel spray into the area where the outer swirl jets 253 in FIG. 3converge (about four to five inches from the face of the swirl plate).These outer swirl jets 253 help to keep the hottest part of the flameoff the inner wall of the combustion tube 210, which enables the burnerto run stoichiometric for extended periods of time. Table 1 showscalculated impact of the fuel spray with the inner wall of thecombustion tube 210, with and without swirl jet interaction. From thesedata, two fuel injectors were built, E-62 and E-76 (where the numberrefers to the angle X,X′ in degrees).

TABLE 1 Air Injection Calc. Impact Distance Angle, Calc. ImpactDistance, Observed with Medium X, X′ No Interaction, in. Impact, in.Interaction, in. 60 2.75 2.5 61 2.88 2.57 62 3.03 2.64 63 3.18 2.71 643.34 2.8 65 3.52 2.89 66 3.71 2.98 67 3.92 3.08 68 4.14 3.25-3.5 3.2 694.38 3.32 70 4.65 3.45 71 4.95 3.6 72 5.27 3.76 73 5.63 3.94 74 6.044.14 75 6.5 4.37 76 7.02 4.64 77 7.62 4.94 78 8.32 5 5.29 79 9.15 5.7 8010.13 6.19

From these data, two fuel injectors were built, with an angle “α” indegrees of 62 and 76 (sometimes referred to hereafter as “E-62” and“E-76,” respectively). After the injectors were built, they were testedin the FOCAS™ rig. The quality of the flame was assessed using threecriteria: a visual measure of smoke in the exhaust, soot on thecombustor, heat exchanger, and catalyst; the appearance of the flame(blueness and transparency); and the location of flame impact with theburner wall. Additionally, the stability of the flame was assessedvisually and through measured AFR feedback using a UEGO sensor. Thecompleteness of the burn was also quantified by measuring the exothermin the catalyst at 70 scfm and stoichiometric. The exotherm in thecatalyst was an indicator of the level of unburned fuel. For a gasolineengine at these conditions, the catalyst exotherm (using this testcatalyst) was about 60° C. The final FOCAS™ injector gave about 50 to60° C. exotherm. The burner conditions during the visual analysis were:

E-68-062 E-76-062 Fuel Injection Pressure:  50 psig 50 psig AirInjection Pressure: 100 psig 55 psig Burner Flow:  70 scfm 70 scfm

The visual quality of both of these flames was very acceptable (no sootbuild-up, no smoke) and the catalyst bed temperatures were in anacceptable range. E-68-062 showed a very blue flame, indicative ofexcellent atomization; but the flame impinged on the wall very close tothe swirl plate, and experience dictated that this type of impact woulddamage the burner wall. This led to using E-76-062, which did not haveas high a flame quality for blueness and transparency, but extended theimpact of the flame with the burner wall to an area that would notdamage the combustor wall. Although some flame quality was sacrificedfor combustor durability, E-76-062 showed a very high quality flame forblueness and transparency compared to commercially available injectorsthat were tested.

FIG. 21 shows a graph of the calculated fuel spray impacts. Generallythermal aging damaged the catalyst washcoat in the front one inch of thecatalyst, which impacted the light-off behavior of the catalyst. FIG. 22shows the measured mass emission during the cold-start phase of the FTP.It can be seen that there are some differences in NMHC, CO and NOx massemissions. FIG. 29 shows the measured catalyst bed temperature duringcold-start. Examining FIG. 29 indicates that beginning during the firstacceleration, and continuing from that point, there was a separation inthe catalyst bed temperature between the aged and unaged catalysts. Boththe engine- and the burner-aged catalysts showed comparable performancebefore and after aging. This difference in temperature is an indicatorthat the aged catalysts were operating with lower efficiency. FIG. 22shows the accumulated modal mass emission of THC and NO_(x) before andafter aging. It can be seen in these figures, that there is indeed loweractivity in the aged converters, and it appears that the engine- andburner-aged catalysts had very similar performance.

EXAMPLE 7 Statistical Analysis of FTP Performance Data

Six catalysts were examined in this study to determine differences inemissions based on the type of aging performed. Three catalysts wereaged on an engine and three were aged on the FOCAS™. Each catalyst wasaged 100 hrs. FTPs were run on all six catalysts in which NO_(x), THC,NMHC, and CO measurements were taken before and after the aging process.Multiple FTPs were run on each catalyst. Table 13 lists the number ofFTP runs made for each catalyst in this study.

TABLE 13 CATALYST FTP STATISTICAL DATA MATRIX Engine Aging FOCAS ™ AgingCatalyst 1 2 3 4 5 6 Aging Hrs 0 2 2 2 2 1 2 100 2 2 3 2 1 2

In order to compare the effect of aging type on emissions, a repeatedmeasures analysis of variance statistical model was used. This modelcontained the following factors:

-   -   Aging Type (engine or FOCAS)    -   Catalyst nested within aging type (each catalyst was only aged        by one method)    -   Aging Time (0 and 100 hrs)    -   Aging Type×Aging Time interaction

Each of the four emissions was analyzed by this model individually.Table 14 lists the results of the repeated measures model. Thehypothesis tested for each factor was whether the average emission foreach level in that factor is significantly different. For example, theAging Type factor compares the average NO_(x) between the catalysts agedin the engine and the catalysts aged on the FOCAS™ over all the timeperiods. For each factor in the model, a p-value is listed whichindicates the probability of accepting the hypothesis that there is nosignificant difference in the average emissions between the factorlevels. All statistical comparisons were made at the 5 percent level ofsignificance. Thus, p-values less than 0.05 indicate statisticallysignificant differences in the average emissions for that factor.

TABLE 14 REPEATED MEASURES ANOVA MODEL RESULTS Factor NO_(x) THC NMHC COAging Type 0.4023 0.5688 0.2221 0.5218 Catalyst Nested in Aging Type0.5792 0.7303 0.8488 0.0596 Aging Time 0.0001 0.0001 0.0001 0.0001 AgingType × Time Interaction 0.3022 0.5712 0.9922 0.0026

The conclusions based on the repeated measures ANOVA model were asfollows:

-   -   There was no significant difference in the average emissions        between the catalysts aged on the engine and the catalysts aged        on the FOCAS over both time periods.    -   There was no significant difference in the average emissions        among the three catalysts aged on the engine over both time        periods.    -   There was no significant difference in the average emissions        among the three catalysts aged on the FOCAS over both time        periods.    -   There was a statistically significant difference in the average        emissions between the catalysts at the zero hours and the        catalysts at the 100 hours of aging.    -   There was no significant difference in the average emissions        between the aging type and the aging time for the NOx, THC, and        NMHC emissions. However, there was a statistically significant        difference in the average CO between the aging type and the        aging time. In this case, the catalysts aged on the engine        demonstrated a significantly greater increase in CO from zero        hours to 100 hours than seen on the catalysts aged on the        FOCAS™.        Plots of the THC, NMHC, NO_(x), and CO emissions by catalyst and        aging period are illustrated in FIG. 25-FIG. 28, respectively.        On the x-axis tickmark labels, the first letter represents the        aging type (B=FOCAS bench, E=engine), the second digit        represents the catalyst number, and the last number represents        the aging time (0 or 100 hours).

EXAMPLE 8 Postmortem Catalyst Evaluations

After all the performance analyses were completed, the catalysts weredisassembled, the center (one-inch diameter, one-inch deep) of eachcatalyst was cored for surface area and composition analysis. The twoanalyses run were BET (Bruhauer-Emmett-Teller) for assessment of surfacearea and porosity, and PIXE (Proton-Induced X-Ray Emissions) forcompositional analysis.

The BET test provided information on the surface area of the substrateand washcoat. This analysis was correlated to thermal degradation. PIXEprovided information on the composition of the substrate, washcoat, andany deposits on the surface of the catalyst. PIXE analysis providedinformation on the differences in the deposits on the catalysts betweenthe engine and the burner (which provided oil-free aging).

Table 15 gives the results of the PIXE analysis, for select elements.

TABLE 15 PIXE ANALYSES RESULTS FOR SELECT ELEMENTS Mass Concentration,Wt % Element E1 E2 E3 B1 B2 B3 P, ppm <674 <723 <766 <715 <758 NOT RUNZn, ppm 326 279 316 13 13 Rh, ppm 0.672 0.650 0.731 0.626 0.662 Pd, %0.187 0.208 0.219 0.183 0.201 Pt, % 0.187 0.208 0.219 0.183 0.201 Ce, %2.883 3.028 3.314 2.954 3.282

Table 15 highlights two basic categories of elements, components of oil,and elements found in the catalyst washcoat. The PIXE analysis showedthat the washcoat materials (Rhodium, Palladium, Platinum, Cerium) werefairly consistent among the five catalysts tested. In looking at theZinc (Zn) deposits between the groups it was seen that the enginecatalysts had substantially more Zn. Phosphorus (P) appeared to be belowthe detection limits (about 700 ppm). However, P is added to oil as ananti-wear additive and generally comes in the form of ZDP; and fielddeposits on catalysts have shown Zn:P weight ratios of about 0.5-0.75.This would imply that there is probably some P on the engine catalysts,perhaps in the range of 400-600 ppm, which would be below the detectionlimit used in this analysis.

The final analysis run on the catalysts was a BET analysis for specificsurface area. A catalyst in good condition has a high surface area. Asthe catalyst ages it loses surface area thermally through agglomeration(migration of the precious metal) and sintering (melting), andnon-thermally through physical blockage of pores by deposits. Table 16gives the BET surface area analysis results.

TABLE 16 BET SURFACE AREA ANALYSIS FOR AGED CATALYSTS Catalyst ConditionBET Surface Area, m²/g E1 100 RAT-A - Engine Aged 11.50 ± 0.22 E2 100RAT-A - Engine Aged 11.46 ± 0.93 E3 100 RAT-A - Engine Aged 11.91 ± 0.13B1 100 RAT-A - Burner Aged 12.84 ± 0.72 B2 100 RAT-A - Burner Aged 13.32± 0.34 B3 100 RAT-A - Burner Aged 12.47 ± 0.22

The BET analysis shows a difference in final specific surface areabetween the two aging methods, with the engine aged parts having a lowersurface area compared to the burner-aged parts. The fresh catalystspecific surface area was probably about 18-25 m2/g (although a freshcatalyst was not analyzed as part of this program). This difference inthe surface area between engine- and the burner-aged catalyst is notlarge, but may be attributable to one or more of the following: thesmall amounts of oil-related deposits observed in the engine agedcatalysts; the increased mass due to the deposits (since the surfacearea is measured as m²/gram); and/or, the beginning of catalyst poreblockage, as occurs in non-thermal deactivation when deposits begin tocoat the surface of the catalyst. It is generally accepted that oildeposits require a minimum mass before the deposits significantly affectcatalyst performance.

The post-mortem analysis showed that the FOCAS™ aging provided thermalaging in the absence of non-thermal aging (i.e. oil deposits), therebycreating a means for the definitive isolation of thermal and non-thermalaging effects.

The simulated RAT-A cycle on the FOCAS™ burner system was compared tothe cycle on the engine. It was demonstrated that the burner can be usedto generate a very similar thermal profile inside the catalyst whencompared to the profile generated by the engine. The shape of thethermal excursion was reproduced, and the AFR into the catalyst could becontrolled and reproduced. One difference that was noted between the twosystems was that there appeared to be some burning of the reactants inthe exhaust pipe, prior to entering the catalyst, in the burner system.This resulted in a slight shift forward of the peak in the location ofthe peak temperature during the thermal excursion.

EXAMPLE 9

The methodology was tested by using the FOCAS™ burner system to simulatethe General Motors Rapid Aging Test version A (RAT-A) cycle. During thetesting portion of the program, six catalysts were aged for 100 hours onthe RAT-A cycle; three on an engine aging stand, and three on the FOCAS™burner system. The catalyst performance at defined intervals and at theconclusion of the aging was measured and compared between the twosystems. In addition, the variation and repeatability of the temperatureand AFR control of each system were assessed and compared.

The performance evaluations consisted of comparing the regulatedemissions across the Federal Test Procedure (FTP) and using anengine-based catalyst performance evaluation rig to measure the catalystconversion efficiency as a function of exhaust air/fuel ratio (AFR) andcatalyst light-off temperature.

The FTP performance evaluations showed that the burner and the engineproduced equivalent aging effects, resulting in deterioration factorsfor THC, CO, and NOx that were not statistically different between thetwo methodologies. There was no significant difference in the averageemissions between the aging type and the aging time for the NOx, THC,and NMHC emissions on the FTP test. However, there was a statisticallysignificant difference in the average CO between the aging type and theaging time. In this case, the catalysts aged on the engine demonstrateda significantly larger increase in CO from zero hours to 100 hours thanwas seen on the catalysts aged on FOCAS™. The evaluations revealed thatthe two methodologies produced equivalent results near stoichiometric(where a gasoline engine is tuned to run). However, as the AFR deviatedfrom stoichiometric to the rich side it was observed that burner aginghad a slightly more severe aging effect on THC and CO.

The final catalyst evaluations involved coring the catalysts, andanalyzing the surface area and composition. The two analyses run wereBET for assessment of surface area and porosity, and PIXE forcompositional analysis. The BET test provides information on the surfacearea of the substrate and washcoat. PIXE provides information on thecomposition of the substrate, washcoat, and any deposits on the surfaceof the catalyst. PIXE analysis can provide information on thedifferences in the deposits on the catalysts between the engine and theburner (which provides oil-free aging). It was found that the catalystswere composed of very similar levels of washcoat, but that theFOCAS™-aged catalysts had an obvious absence of oil derived deposits.However, the levels of oil deposits found on the engine aged catalystswere small, and it is likely that deposits did not impact catalystperformance in this study. However, as an engine ages, oil consumptionwill increase, adding a variable oil poisoning component to the catalystaging. It is generally accepted that oil deposits require a minimum massbefore the deposits significantly affect catalyst performance. The BETanalysis showed a difference in final specific surface area between thetwo aging methods, with the engine aged parts having a lower surfacearea compared to the burner aged parts. The reduced surface area couldbe a result of the increased core mass due to the deposits (since thesurface area is measured as m²/gram). The reduced surface area couldalso be the beginning of catalyst pore blockage, as occurs innon-thermal deactivation when deposits begin to coat the surface of thecatalyst. It could also be a result of a combination of the two effects.

Overall, it was found that the FOCAS™ burner system provided a flexiblemeans for simulating the engine aging cycle, and produced thermal agingresults equivalent to the engine cycle. The post-mortem analysis showedthat the FOCAS™ aging provides thermal aging in the absence ofnon-thermal aging (i.e. oil deposits), thereby creating a means for thedefinitive isolation of thermal and non-thermal aging effects. Someadvantages that using a burner offers over an engine for aging include:very tight AFR control (±0.02 AFR), very broad range of stable AFRoperation (8:1 to 25:1), few moving parts (a blower and a fuel meteringvalve), and minimal adjustments to achieve setpoints. Also, a burner canbe run at very high temperatures without severely damaging the systemcomponents, making for a low cost, low risk simulation of very hightemperature cycles.

Persons of ordinary skill in the art will recognize that manymodifications may be made to the present application without departingfrom the spirit and scope of the application. The embodiment describedherein is meant to be illustrative only and should not be taken aslimiting the application, which is defined in the claims.

1. A burner-based system for producing exhaust that simulates exhaustproduced by an internal combustion engine, for delivery of the exhaustto an emissions control device, comprising: a burner system having atleast a burner for receiving air and fuel having an air-fuel ratio andfor combusting fuel to produce simulated engine exhaust and having afuel injector for providing fuel to the burner; an exhaust line forcarrying the exhaust from the burner to the emissions control device; aheat exchanger for cooling the exhaust gas downstream the burner; ablower for providing pressurized air flow to the burner; a secondary airinjector for providing supplemental oxygen into the exhaust line; acomputerized control system operable to control the air-fuel ratio toprovide a desired stiochiometry of the burner and to provide a number ofburner system operating modes, including at least a thermal excursionmode accomplished by providing the burner with a rich air-fuel ratio andby providing supplemental oxygen into the exhaust line between theburner and -the emissions control device via the secondary air injector;wherein the burner has a combustion tube for receiving air-assisted fuelspray from the fuel injector, and at least one igniter extending intothe wall of the combustion tube for creating a burner flame; wherein theburner has a swirl plate having a central bore for holding the fuelinjector, the swirl plate further having a first set of turbulent jetbores, swirl jet bores, and a second set of turbulent jet bores throughwhich the pressurized air flow passes into the combustion tube; whereinthe first set of turbulent jet bores are angled toward the inner wall ofthe combustion tube to prevent the burner flame from continuouslycontacting the inner wall of the combustion tube; wherein the swirl jetbores are angled toward the fuel spray from the injector to interactwith the fuel spray to create a swirl pattern of the fuel spray withinthe combustion tube; and wherein the second set of turbulent jet boresare angled toward the fuel injector to converge in front of the fuelinjector to prevent the flame from attaching to the fuel injector. 2.The system of claim 1, further comprising a liquid injector forinjecting liquid substances into the exhaust line.
 3. The system ofclaim 1, wherein the system is operable to maintain stable operation atan air to fuel ratio of from about 8:1 to 25:1.
 4. The system of claim1, wherein the supplemental oxygen is provided in the form ofsupplemental air.
 5. The system of claim 1, wherein the thermalexcursion mode provides a predetermined carbon monoxide component of theexhaust of at least 3%.
 6. The system of claim 1, wherein the thermalexcursion mode provides a predetermined oxygen component of the exhaustof at least 3%.
 7. The system of claim 1, wherein one of the modes is acooling mode, performed by cooling the emissions control device with thefan.
 8. The system of claim 1, wherein one of the modes is a coolingmode, performed by cooling the exhaust with a heat exchanger on theexhaust line between the burner and the emissions control device.
 9. Thesystem of claim 1, wherein one of the modes is a cooling mode, performedby cooling the exhaust with a heat exchanger on the exhaust line betweenthe burner and the emissions control device and with the fan.
 10. Thesystem of claim 1, wherein the operating modes further include at leastthe following modes: steady state stoichiometric and rich.
 11. Thesystem of claim 1, wherein the operating modes further include at leastthe following modes: steady state stoichiometric and lean.
 12. Thesystem of claim 1, wherein the operating modes further include at leastthe following modes: steady state stoichiometric and cold start.
 13. Thesystem of claim 1, wherein the thermal excursion substantially conformsto a RAT-A specification.
 14. The system of claim 1 wherein the thermalexcursion is performed by providing exhaust having a temperature up to1000 degrees C.